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MI5 ( Military Intelligence, Section 5), officially the Security Service, is the United Kingdom's domestic
counter-intelligence Counterintelligence (counter-intelligence) or counterespionage (counter-espionage) is any activity aimed at protecting an agency's intelligence program from an opposition's intelligence service. It includes gathering information and conducting ac ...
and
security agency A security agency is a governmental organization that conducts intelligence activities for the internal security of a state. They are the domestic cousins of foreign intelligence agencies, and typically conduct counterintelligence to thwart other ...
and is part of its intelligence machinery alongside the
Secret Intelligence Service The Secret Intelligence Service (SIS), commonly known as MI6 (MI numbers, Military Intelligence, Section 6), is the foreign intelligence service of the United Kingdom, tasked mainly with the covert overseas collection and analysis of Human i ...
(MI6),
Government Communications Headquarters Government Communications Headquarters (GCHQ) is an intelligence and security organisation responsible for providing signals intelligence (SIGINT) and information assurance (IA) to the government and armed forces of the United Kingdom. Primari ...
(GCHQ), and
Defence Intelligence Defence Intelligence (DI) is an organisation within the United Kingdom intelligence community which focuses on gathering and analysing military intelligence. It differs from the UK's intelligence agencies (MI6, GCHQ and MI5) in that it is an ...
(DI). MI5 is directed by the Joint Intelligence Committee (JIC), and the service is bound by the
Security Service Act 1989 The Security Service Act 1989 (c. 5) is an Act of the United Kingdom Parliament. The Act established a statutory basis of the UK Security Service (MI5) for the first time. Prior to the Act, successive UK governments had denied the existence of ...
. The service is directed to protect British parliamentary democracy and economic interests and to counter
terrorism Terrorism, in its broadest sense, is the use of violence against non-combatants to achieve political or ideological aims. The term is used in this regard primarily to refer to intentional violence during peacetime or in the context of war aga ...
and
espionage Espionage, spying, or intelligence gathering, as a subfield of the intelligence field, is the act of obtaining secret or confidential information ( intelligence). A person who commits espionage on a mission-specific contract is called an ...
within the
United Kingdom The United Kingdom of Great Britain and Northern Ireland, commonly known as the United Kingdom (UK) or Britain, is a country in Northwestern Europe, off the coast of European mainland, the continental mainland. It comprises England, Scotlan ...
. Within the civil service community, the service is colloquially known as ''Box'', or ''Box 500'', after its official wartime address of PO Box 500; its current address is PO Box 3255,
London London is the Capital city, capital and List of urban areas in the United Kingdom, largest city of both England and the United Kingdom, with a population of in . London metropolitan area, Its wider metropolitan area is the largest in Wester ...
SW1P 1AE. The Security Service is derived from the Secret Service Bureau, founded in 1909. At the start of the
First World War World War I or the First World War (28 July 1914 – 11 November 1918), also known as the Great War, was a World war, global conflict between two coalitions: the Allies of World War I, Allies (or Entente) and the Central Powers. Fighting to ...
, it was responsible for the arrest of enemy spies, or suspected enemy spies. Throughout the First World War, Germany continually attempted to infiltrate Britain, but MI5 was able to identify most, if not all, of the agents dispatched. During the
Second World War World War II or the Second World War (1 September 1939 – 2 September 1945) was a World war, global conflict between two coalitions: the Allies of World War II, Allies and the Axis powers. World War II by country, Nearly all of the wo ...
, it developed the
Double-Cross System The Double-Cross System or XX System was a World War II counter-espionage and deception operation of the British Security Service ( MI5). Nazi agents in Britain – real and false – were captured, turned themselves in or simply announced themse ...
. This involved attempting to "turn" captured agents wherever possible, and use them to mislead enemy intelligence agencies. After the war, the service was instrumental in breaking up a large
Soviet The Union of Soviet Socialist Republics. (USSR), commonly known as the Soviet Union, was a List of former transcontinental countries#Since 1700, transcontinental country that spanned much of Eurasia from 1922 until Dissolution of the Soviet ...
spy ring at the start of the 1970s. It then allegedly became involved in monitoring
trade union A trade union (British English) or labor union (American English), often simply referred to as a union, is an organization of workers whose purpose is to maintain or improve the conditions of their employment, such as attaining better wages ...
s and left-wing politicians. It also assumed responsibility for the investigation of all
Irish republican Irish republicanism () is the political movement for an Irish republic, void of any British rule. Throughout its centuries of existence, it has encompassed various tactics and identities, simultaneously elective and militant and has been both w ...
activity within Britain during
The Troubles The Troubles () were an ethno-nationalist conflict in Northern Ireland that lasted for about 30 years from the late 1960s to 1998. Also known internationally as the Northern Ireland conflict, it began in the late 1960s and is usually deemed t ...
. Its role was then expanded to countering other forms of terrorism, particularly in more recent years the more widespread threat of
Islamic extremism Islamic extremism refers to extremist beliefs, behaviors and ideologies adhered to by some Muslims within Islam. The term 'Islamic extremism' is contentious, encompassing a spectrum of definitions, ranging from academic interpretations of Is ...
. In 1996, legislation formalised the extension of the Security Service's statutory remit to include supporting the law enforcement agencies in their work against serious crime.


Organisation


Structure

The Security Service comes under the authority of the
Home Secretary The secretary of state for the Home Department, more commonly known as the home secretary, is a senior minister of the Crown in the Government of the United Kingdom and the head of the Home Office. The position is a Great Office of State, maki ...
within the
Cabinet Cabinet or The Cabinet may refer to: Furniture * Cabinetry, a box-shaped piece of furniture with doors and/or drawers * Display cabinet, a piece of furniture with one or more transparent glass sheets or transparent polycarbonate sheets * Filin ...
. The service is headed by a Director General (DG) at the grade of a
Permanent Secretary A permanent secretary is the most senior Civil Service (United Kingdom), civil servant of a department or Ministry (government department), ministry charged with running the department or ministry's day-to-day activities. Permanent secretaries are ...
of the
Civil Service The civil service is a collective term for a sector of government composed mainly of career civil service personnel hired rather than elected, whose institutional tenure typically survives transitions of political leadership. A civil service offic ...
, who is directly supported by an internal security organisation, secretariat, legal advisory branch, and information services branch. The Deputy Director General is responsible for the operational activity of the service, being responsible for four branches; international counter-terrorism, National Security Advice Centre (counter proliferation and counter espionage), Irish and domestic counter-terrorism, and technical and surveillance operations. The service is directed for intelligence operational priorities by the Joint Intelligence Committee. It liaises with SIS, GCHQ, DI, and a number of other bodies within the British government, and industrial base. It is overseen by the Intelligence and Security Committee of Members of Parliament, who are directly appointed by the
Prime Minister A prime minister or chief of cabinet is the head of the cabinet and the leader of the ministers in the executive branch of government, often in a parliamentary or semi-presidential system. A prime minister is not the head of state, but r ...
, and by the
Investigatory Powers Commissioner The Investigatory Powers Commissioner (IPC) is an "Arms-Length" public official in the United Kingdom who oversees the use of investigatory powers of public authorities such as Law enforcement in the United Kingdom, Police, Law Enforcement Agen ...
. Judicial oversight of the service's conduct is exercised by the
Investigatory Powers Tribunal The Investigatory Powers Tribunal (IPT) is a first-instance tribunal and superior court of record in the United Kingdom. It is primarily an inquisitorial court. It hears complaints about surveillance by public bodies, primarily the intelligen ...
.


Legislation

Operations of the service are required to be proportionate, and compliant with British legislation, including the
Regulation of Investigatory Powers Act 2000 The Regulation of Investigatory Powers Act 2000 (citation of United Kingdom legislation, c. 23) (RIP or RIPA) is an Act of parliament, Act of the Parliament of the United Kingdom, regulating the powers of public bodies to carry out surveillanc ...
, the
Investigatory Powers Act 2016 The Investigatory Powers Act 2016 (c. 25) (nicknamed the Snoopers' Charter) is an Act of the Parliament of the United Kingdom which received royal assent on 29 November 2016. Its different parts came into force on various dates from 30 December ...
, the
Data Protection Act 2018 The Data Protection Act 2018 (c. 12) is a United Kingdom act of Parliament (UK) which updates data protection laws in the UK. It is a national law which complements the European Union's General Data Protection Regulation (GDPR) and replaces the D ...
, and various other items of legislation. Information held by the service is exempt from disclosure under section 23 of the
Freedom of Information Act 2000 The Freedom of Information Act 2000 (c. 36) is an Act of the Parliament of the United Kingdom that creates a public right of access to information held by public authorities. It is the implementation of freedom of information legislation in t ...
. The Security Service Act of 1989 establishes several legal key mechanisms aimed at ensuring the accountability and control of the Service. Certain provisions from this act were later integrated into the Intelligence Services Act of 1994 with European Commission on Human Rights later having endorsed these mechanisms in multiple applications under the European Convention on Human Rights. Additionally, the Service is subject to oversight and accountability through various other means. These oversight mechanisms have evolved over time to meet changing governmental requirements, with the Service now being held accountable through a variety of oversight arrangements.


Oversight

All employees of the service are bound by the
Official Secrets Act An Official Secrets Act (OSA) is legislation that provides for the protection of Classified information, state secrets and official information, mainly related to national security. However, in its unrevised form (based on the UK Official Secret ...
. In certain circumstances, officers handling agents or informers may authorise them to carry out activity which would otherwise be criminal within the United Kingdom. The Security Service "is authorised to investigate any person or movement that might threaten the...security" of the United Kingdom. The current Director General is
Ken McCallum Sir Kenneth Douglas McCallum (born 1974) is a British intelligence officer who has been serving as the Director General of MI5 since 2020. Early life and education McCallum was born in Glasgow, Scotland, in 1974. He attended a state school, ...
, who succeeded Andrew Parker in April 2020.


Centenary and awards

The service marked its centenary in 2009 by publishing an official history titled '' The Defence of the Realm: The Authorized History of MI5'', written by Christopher Andrew, Professor of Modern and Contemporary History at
Cambridge University The University of Cambridge is a Public university, public collegiate university, collegiate research university in Cambridge, England. Founded in 1209, the University of Cambridge is the List of oldest universities in continuous operation, wo ...
. Members of the Security Service are recognised annually by
King Charles III Charles III (Charles Philip Arthur George; born 14 November 1948) is King of the United Kingdom and the 14 other Commonwealth realms. Charles was born at Buckingham Palace during the reign of his maternal grandfather, King George VI, and ...
at the
Prince of Wales's Intelligence Community Awards The Prince of Wales's Intelligence Community Awards (or the Intelligence Agencies Awards) are awards given annually by the Prince of Wales to members of the three intelligence agencies, MI5, Secret Intelligence Service, and GCHQ, of the United King ...
at
St James's Palace St James's Palace is the most senior royal palace in London, England. The palace gives its name to the Court of St James's, which is the monarch's royal court, and is located in the City of Westminster. Although no longer the principal residence ...
or
Clarence House Clarence House is a royal residence on The Mall in the City of Westminster, London. It was built in 1825–1827, adjacent to St James's Palace, for the royal Duke of Clarence, the future King William IV. The four-storey house is faced in ...
alongside members of the
Secret Intelligence Service The Secret Intelligence Service (SIS), commonly known as MI6 (MI numbers, Military Intelligence, Section 6), is the foreign intelligence service of the United Kingdom, tasked mainly with the covert overseas collection and analysis of Human i ...
(MI6), and
GCHQ Government Communications Headquarters (GCHQ) is an intelligence and security organisation responsible for providing signals intelligence (SIGINT) and information assurance (IA) to the government and armed forces of the United Kingdom. Primar ...
. Awards and citations are given to teams within the agencies as well as individuals.


History


Early years

The Security Service is derived from the Secret Service Bureau, founded in 1909, and concentrating originally on the activities of the
Imperial German (, literally translated ) is an archaic term for those ethnic Germans who resided within the German state that was founded in 1871. In contemporary usage, it referred to German citizens, the word signifying people from the German ', i.e., Imp ...
government, as a joint initiative of the
Admiralty Admiralty most often refers to: *Admiralty, Hong Kong * Admiralty (United Kingdom), military department in command of the Royal Navy from 1707 to 1964 *The rank of admiral *Admiralty law Admiralty can also refer to: Buildings * Admiralty, Tra ...
and the
War Office The War Office has referred to several British government organisations throughout history, all relating to the army. It was a department of the British Government responsible for the administration of the British Army between 1857 and 1964, at ...
. The Bureau was initially split into naval and army sections which, over time, specialised respectively in foreign target
espionage Espionage, spying, or intelligence gathering, as a subfield of the intelligence field, is the act of obtaining secret or confidential information ( intelligence). A person who commits espionage on a mission-specific contract is called an ...
and internal
counter-espionage Counterintelligence (counter-intelligence) or counterespionage (counter-espionage) is any activity aimed at protecting an agency's intelligence program from an opposition's intelligence service. It includes gathering information and conducting ac ...
activities. The former specialisation was a result of a growing interest at the Admiralty, at the time, in intelligence regarding the fleet of the
Imperial German Navy The Imperial German Navy or the ''Kaiserliche Marine'' (Imperial Navy) was the navy of the German Empire, which existed between 1871 and 1919. It grew out of the small Prussian Navy (from 1867 the North German Federal Navy), which was mainly for ...
. This division was formalised, as separate home and foreign sections, prior to the beginning of the
First World War World War I or the First World War (28 July 1914 – 11 November 1918), also known as the Great War, was a World war, global conflict between two coalitions: the Allies of World War I, Allies (or Entente) and the Central Powers. Fighting to ...
. Following a number of administrative changes, the home section became known as Directorate of Military Intelligence, Section 5 and the abbreviation MI5, the name by which it is still known in popular culture. (The foreign/naval section of the Secret Service Bureau was to become the basis of the later Secret Intelligence Service, or
MI6 The Secret Intelligence Service (SIS), commonly known as MI6 ( Military Intelligence, Section 6), is the foreign intelligence service of the United Kingdom, tasked mainly with the covert overseas collection and analysis of human intelligenc ...
.) The founding head of the Army section was
Vernon Kell Major General Sir Vernon George Waldegrave Kell, (21 November 1873 â€“ 27 March 1942) was a British Army general and the founder and first Director of the British Security Service, otherwise known as MI5. Known as K, he was described in ' ...
of the
South Staffordshire Regiment The South Staffordshire Regiment was a line infantry regiment of the British Army in existence for only 68 years. The regiment was created in 1881 under the Childers Reforms by the amalgamation of the 38th (1st Staffordshire) Regiment of Foot a ...
, who remained in that role until the early part of the
Second World War World War II or the Second World War (1 September 1939 – 2 September 1945) was a World war, global conflict between two coalitions: the Allies of World War II, Allies and the Axis powers. World War II by country, Nearly all of the wo ...
. Its role was originally quite restricted, as the section existed solely to ensure national security through counter-espionage. With a small staff, and working in conjunction with the
Special Branch Special Branch is a label customarily used to identify units responsible for matters of national security and Intelligence (information gathering), intelligence in Policing in the United Kingdom, British, Commonwealth of Nations, Commonwealth, ...
of the Metropolitan Police, the service was responsible for overall direction and the identification of foreign agents, while Special Branch provided the manpower for the investigation of their affairs, arrest and interrogation. On the day after the declaration of the First World War, the Home Secretary,
Reginald McKenna Reginald McKenna (6 July 1863 – 6 September 1943) was a British banker and Liberal politician. His first Cabinet post under Henry Campbell-Bannerman was as President of the Board of Education, after which he served as First Lord of the Admira ...
, announced that "within the last twenty-four hours no fewer than twenty-one spies, or suspected spies, have been arrested in various places all over the country, chiefly in important military or naval centres, some of them long known to the authorities to be spies". These arrests have provoked recent historical controversy. According to the official history of MI5, the actual number of agents identified was 22, and Kell had started sending out letters to local police forces on 29 July, giving them advance warning of arrests to be made as soon as war was declared. Portsmouth Constabulary jumped the gun and arrested one on 3 August, and not all of the 22 were in custody by the time that McKenna made his speech, but the official history regards the incident as a devastating blow to
Imperial Germany The German Empire (),; ; World Book, Inc. ''The World Book dictionary, Volume 1''. World Book, Inc., 2003. p. 572. States that Deutsches Reich translates as "German Realm" and was a former official name of Germany. also referred to as Imperia ...
, which deprived them of their entire spy ring, and specifically upset the Kaiser. In 2006, his article 'Entering the Lists' was published in the journal ''Intelligence and National Security'', outlining the products of his research into recently opened files. Hiley was sent an advance copy of the official history, and objected to the retelling of the story. He later wrote another article, 'Re-entering the Lists', which asserted that the list of those arrested published in the official history was concocted from later case histories.


Inter-war period

MI5 proved consistently successful throughout the rest of the 1910s and 1920s in its core counter-espionage role. Throughout the First World War, Germany continually attempted to infiltrate Britain, but MI5 was able to identify most, if not all, of the agents dispatched. MI5 used a method that depended on strict control of entry and exit to the country and, crucially, large-scale inspection of mail. In post-war years, attention turned to attempts by the
Soviet Union The Union of Soviet Socialist Republics. (USSR), commonly known as the Soviet Union, was a List of former transcontinental countries#Since 1700, transcontinental country that spanned much of Eurasia from 1922 until Dissolution of the Soviet ...
and the
Comintern The Communist International, abbreviated as Comintern and also known as the Third International, was a political international which existed from 1919 to 1943 and advocated world communism. Emerging from the collapse of the Second Internatio ...
to surreptitiously support revolutionary activities within Britain. MI5's expertise, combined with the early incompetence of the Soviets, meant the bureau was successful in correctly identifying and closely monitoring these activities. In the meantime, MI5's role had grown substantially. Due to the spy hysteria, MI5 had formed with far more resources than it actually needed to track down German spies. As is common within governmental bureaucracies, this caused the service to expand its role to use its spare resources. MI5 acquired many additional responsibilities during the war. Most significantly, its strict counter-espionage role blurred considerably. It acquired a much more political role, involving the surveillance not merely of foreign agents, but also of
pacifist Pacifism is the opposition to war or violence. The word ''pacifism'' was coined by the French peace campaigner Émile Arnaud and adopted by other peace activists at the tenth Universal Peace Congress in Glasgow in 1901. A related term is ''a ...
and anti-
conscription Conscription, also known as the draft in the United States and Israel, is the practice in which the compulsory enlistment in a national service, mainly a military service, is enforced by law. Conscription dates back to antiquity and it conti ...
organisations, and of
organised labour The labour movement is the collective organisation of working people to further their shared political and economic interests. It consists of the trade union or labour union movement, as well as political parties of labour. It can be considere ...
. This was justified by citing the common belief that foreign influence was at the root of these organisations. Thus, by the end of the First World War, MI5 was a fully-fledged investigating force (although it never had powers of arrest), in addition to being a counter-espionage agency. The expansion of this role continued after a brief post-war power struggle with the head of the
Special Branch Special Branch is a label customarily used to identify units responsible for matters of national security and Intelligence (information gathering), intelligence in Policing in the United Kingdom, British, Commonwealth of Nations, Commonwealth, ...
, Sir
Basil Thomson Sir Basil Home Thomson, (21 April 1861 – 26 March 1939) was a British colonial administrator and prison governor, who was head of Metropolitan Police CID during World War I. This gave him a key role in arresting wartime spies, and he was c ...
. After the First World War, budget-conscious politicians regarded Kell's department as unnecessary. In 1919, MI5's budget was slashed from £100,000 to just £35,000, and its establishment from over 800 officers to a mere 12. At the same time, Sir
Basil Thomson Sir Basil Home Thomson, (21 April 1861 – 26 March 1939) was a British colonial administrator and prison governor, who was head of Metropolitan Police CID during World War I. This gave him a key role in arresting wartime spies, and he was c ...
of Special Branch was appointed Director of Home Intelligence, in supreme command of all domestic counter-insurgency and counter-intelligence investigations. Consequently, as official MI5 historian Christopher Andrew has noted in his official history ''Defence of the Realm'' (2010), MI5 had no clearly defined role in the
Anglo-Irish War The Irish War of Independence (), also known as the Anglo-Irish War, was a guerrilla war fought in Ireland from 1919 to 1921 between the Irish Republican Army (IRA, the army of the Irish Republic) and British forces: the British Army, along wi ...
of 1919–1921. To further worsen the situation, several of Kell's officers defected to Thomson's new agency, the Home Intelligence Directorate. MI5 therefore undertook no tangible intelligence operations of consequence during the
Irish War of Independence The Irish War of Independence (), also known as the Anglo-Irish War, was a guerrilla war fought in Ireland from 1919 to 1921 between the Irish Republican Army (1919–1922), Irish Republican Army (IRA, the army of the Irish Republic) and Unite ...
. MI5 did undertake the training of
British Army The British Army is the principal Army, land warfare force of the United Kingdom. the British Army comprises 73,847 regular full-time personnel, 4,127 Brigade of Gurkhas, Gurkhas, 25,742 Army Reserve (United Kingdom), volunteer reserve perso ...
case-officers from the Department of Military Intelligence (DMI), for the Army's so-called "Silent Section", otherwise known as M04(x). Quickly trained by MI5 veterans at Hounslow Barracks, outside London, these freshly-minted M04(x) Army case-officers were deployed to
Dublin Dublin is the capital and largest city of Republic of Ireland, Ireland. Situated on Dublin Bay at the mouth of the River Liffey, it is in the Provinces of Ireland, province of Leinster, and is bordered on the south by the Dublin Mountains, pa ...
beginning in the spring of 1919. Over time, 175 officers were trained and dispatched to Ireland. In Ireland, they came under the command of General Cecil Romer and his Deputy, Lieutenant Colonel Stephen Searle Hill-Dillon. In April 1919, Colonel Walter Wilson of the Department of Military Intelligence arrived in Dublin to take over the day-to-day management of these 175 Army intelligence-officers, and the unit was designated as the "Dublin District Special Branch" (DMI/MO4(x)/DDSB), because it operated exclusively within the confines of the Army's Dublin Military District. Royal Marine Colonel Hugh Montgomery of the Department of Naval Intelligence, was also seconded to Romer's intelligence staff at this time. British Army after-action reports and contemporary accounts indicate that M04(x)/DDSB was considered by some a highly amateurish outfit. Serious cover constraints, coupled with alcohol abuse and social fraternisation with local prostitutes would prove the downfall of several of these amateur sleuths. Despite these failings, it was not MI5, but one of Basil Thomson's agents, John Charles Byrnes, a
double agent In the field of counterintelligence, a double agent is an employee of a secret intelligence service for one country, whose primary purpose is to spy on a target organization of another country, but who is now spying on their own country's organi ...
within the IRA, who identified
Michael Collins Michael Collins or Mike Collins most commonly refers to: * Michael Collins (Irish leader) (1890–1922), Irish revolutionary leader, soldier, and politician * Michael Collins (astronaut) (1930–2021), American astronaut, member of Apollo 11 and Ge ...
, and came close to arranging his capture. The IRA identified Byrnes as a British spy and murdered him in March 1920. The intelligence staff of Michael Collins
Irish Republican Army The Irish Republican Army (IRA) is a name used by various Resistance movement, resistance organisations in Ireland throughout the 20th and 21st centuries. Organisations by this name have been dominantly Catholic and dedicated to anti-imperiali ...
penetrated the unit. Using DMP detectives Ned Broy and David Nelligan, Michael Collins was able to learn the names and lodgings of the M04(x) agents, referred to by IRA operatives as "The Cairo Gang". On "
Bloody Sunday Bloody Sunday may refer to: Historical events Canada * Bloody Sunday (1923), a day of police violence during a steelworkers' strike for union recognition in Sydney, Cape Breton Island, Nova Scotia * Bloody Sunday (1938), police violence agai ...
", 21 November 1920, Collins ordered his counter-intelligence unit, The Squad, to assassinate 25 M04(x) agents, several British courts-martial officers, at least one agent reporting to Basil Thomson, and several intelligence officers attached to the Royal Irish Constabulary Auxiliary Division, at their lodgings throughout Dublin. That afternoon, a mixed force of the British Army, the
Royal Irish Constabulary The Royal Irish Constabulary (RIC, ; simply called the Irish Constabulary 1836–67) was the police force in Ireland from 1822 until 1922, when all of the island was part of the United Kingdom of Great Britain and Ireland, United Kingdom. A sep ...
, and the
Black and Tans The Black and Tans () were constables recruited into the Royal Irish Constabulary (RIC) as reinforcements during the Irish War of Independence. Recruitment began in Great Britain in January 1920, and about 10,000 men enlisted during the conflic ...
retaliated by indiscriminately shooting dead 14 civilians at a
Gaelic Football Gaelic football (; short name '')'', commonly known as simply Gaelic, GAA, or football, is an Irish team sport. A form of football, it is played between two teams of 15 players on a rectangular grass pitch. The objective of the sport is to score ...
match at
Croke Park Croke Park (, ) is a Gaelic games stadium in Dublin, Ireland. Named after Archbishop Thomas Croke, it is referred to as Croker by GAA fans and locals. It serves as both the principal national stadium of Ireland and headquarters of the Gaelic At ...
. The net impact of Collins's strike of Bloody Sunday, 21 November 1920, was relatively negligible, even though the IRA had not gone up against MI5 professionals, but instead only against a quickly trained outfit of amateur army "D-Listers". Although the shooting of 14 British officers had the desired effect on British morale, other aspects were botched by the IRA. Three of Collins's men were apprehended after engaging in a shoot-out on the street, and at least two of the wounded British officers had no connection whatsoever to British intelligence. Moreover, with MO4(x) having fielded a total of 175 agents of the DDSB, Collins's operation only temporarily slowed British momentum. Within days, the remaining 160-odd M04(x) agents were re-established in secure quarters inside solidly loyalist hotels in Dublin, from where they continued to pursue Collins and the IRA relentlessly right up until the truce of July 1921. In December 1920, the entire DDSB was transferred from
British Army The British Army is the principal Army, land warfare force of the United Kingdom. the British Army comprises 73,847 regular full-time personnel, 4,127 Brigade of Gurkhas, Gurkhas, 25,742 Army Reserve (United Kingdom), volunteer reserve perso ...
command to civil command under Deputy Police Commissioner General Ormonde Winter, and thereafter was known as "D Branch" within Dublin Castle. By January 1921, the highly experienced
MI6 The Secret Intelligence Service (SIS), commonly known as MI6 ( Military Intelligence, Section 6), is the foreign intelligence service of the United Kingdom, tasked mainly with the covert overseas collection and analysis of human intelligenc ...
operative David Boyle arrived at Dublin Castle to take over the day-to-day management of D Branch. The unit's former commander, Colonel Wilson, resigned in protest against having had his command taken from him. D Branch thrived under Boyle's leadership. In 1921, Sir Warren Fisher, the government inspector-general for civil-service affairs, conducted a thorough review of the operations and expenditures of Basil Thomson's Home Intelligence Directorate. He issued a scathing report, accusing Thomson of wasting both money and resources, and conducting redundant as well as ineffectual operations. Shortly thereafter, in a private meeting with Prime Minister
David Lloyd George David Lloyd George, 1st Earl Lloyd-George of Dwyfor (17 January 1863 – 26 March 1945) was Prime Minister of the United Kingdom from 1916 to 1922. A Liberal Party (United Kingdom), Liberal Party politician from Wales, he was known for leadi ...
, Sir Basil Thomson was sacked, and the Home Intelligence Directorate was formally abolished. With Thomson out of the way,
Special Branch Special Branch is a label customarily used to identify units responsible for matters of national security and Intelligence (information gathering), intelligence in Policing in the United Kingdom, British, Commonwealth of Nations, Commonwealth, ...
was returned to the command of the Commissioner of The Criminal Investigation Division at
Scotland Yard Scotland Yard (officially New Scotland Yard) is the headquarters of the Metropolitan Police, the territorial police force responsible for policing Greater London's London boroughs, 32 boroughs. Its name derives from the location of the original ...
. Only then was Vernon Kell able once again to rebuild MI5 and re-establish it in its former place as Britain's chief domestic spy agency. MI5 operated in Italy during inter-war period, and helped
Benito Mussolini Benito Amilcare Andrea Mussolini (29 July 188328 April 1945) was an Italian politician and journalist who, upon assuming office as Prime Minister of Italy, Prime Minister, became the dictator of Fascist Italy from the March on Rome in 1922 un ...
get his start in politics with a £100 weekly wage. MI5's efficiency in counter-espionage declined from the 1930s. It was to some extent a victim of its own success as it was unable to break the ways of thinking it had evolved in the 1910s and 1920s. In particular, it was unable to adjust to the new methods of the Soviet intelligence services, the
People's Commissariat for Internal Affairs The People's Commissariat for Internal Affairs (, ), abbreviated as NKVD (; ), was the interior ministry and secret police of the Soviet Union from 1934 to 1946. The agency was formed to succeed the Joint State Political Directorate (OGPU) secre ...
(NKVD) and Main Intelligence Directorate (GRU). It continued to think in terms of agents who would attempt to gather information simply through observation or bribery, or to agitate within labour organisations and the armed services, while posing as ordinary citizens. The NKVD, meanwhile, had evolved more sophisticated methods; it began to recruit agents from within the
upper classes Upper class in modern societies is the social class composed of people who hold the highest social status. Usually, these are the wealthiest members of class society, and wield the greatest political power. According to this view, the upper cla ...
(most notably from
Cambridge University The University of Cambridge is a Public university, public collegiate university, collegiate research university in Cambridge, England. Founded in 1209, the University of Cambridge is the List of oldest universities in continuous operation, wo ...
), whom it regarded as a long-term investment. Such NKVD agents succeeded in gaining positions within the government, and, in Kim Philby's case, within British intelligence itself, from where they were able to provide the NKVD with sensitive information. The most successful of these agents; Harold 'Kim' Philby, Donald Maclean,
Guy Burgess Guy Francis de Moncy Burgess (16 April 1911 – 30 August 1963) was a British diplomat and Soviet double agent, and a member of the Cambridge Five spy ring that operated from the mid-1930s to the early years of the Cold War era. His defection ...
,
Anthony Blunt Anthony Frederick Blunt (26 September 1907 – 26 March 1983), (formerly styled Sir Anthony Blunt from 1956 until November 1979), was a leading British art historian and a Soviet spy. Blunt was a professor of art history at the University ...
, and
John Cairncross John Cairncross (25 July 1913 – 8 October 1995) was a British civil servant who became an intelligence officer and spy during the Second World War. As a Soviet double agent, he passed to the Soviet Union the raw Tunny decryptions that may h ...
; went undetected until after the
Second World War World War II or the Second World War (1 September 1939 – 2 September 1945) was a World war, global conflict between two coalitions: the Allies of World War II, Allies and the Axis powers. World War II by country, Nearly all of the wo ...
, and became known as the
Cambridge Five The Cambridge Five was a ring of spies in the United Kingdom that passed information to the Soviet Union during the Second World War and the Cold War and was active from the 1930s until at least the early 1950s. None of the known members were e ...
.


Second World War

One of the earliest actions of
Winston Churchill Sir Winston Leonard Spencer Churchill (30 November 1874 – 24 January 1965) was a British statesman, military officer, and writer who was Prime Minister of the United Kingdom from 1940 to 1945 (Winston Churchill in the Second World War, ...
on coming to power in early 1940 was to sack the agency's long-term head,
Vernon Kell Major General Sir Vernon George Waldegrave Kell, (21 November 1873 â€“ 27 March 1942) was a British Army general and the founder and first Director of the British Security Service, otherwise known as MI5. Known as K, he was described in ' ...
. He was replaced initially by the ineffective
Oswald Allen Harker Brigadier Oswald Allen Harker CBE (1886–1968), known as Jasper Harker, was Acting Director General of MI5 from 1940 to 1941. Background Oswald Allen Harker was born in Cirencester in 1886, the son of James Allen Harker, a professor at the Roy ...
, as Acting Director General. Harker in turn was quickly replaced by David Petrie, a
Secret Intelligence Service The Secret Intelligence Service (SIS), commonly known as MI6 (MI numbers, Military Intelligence, Section 6), is the foreign intelligence service of the United Kingdom, tasked mainly with the covert overseas collection and analysis of Human i ...
(SIS) man, with Harker remaining as his deputy. With the ending of the
Battle of Britain The Battle of Britain () was a military campaign of the Second World War, in which the Royal Air Force (RAF) and the Fleet Air Arm (FAA) of the Royal Navy defended the United Kingdom (UK) against large-scale attacks by Nazi Germany's air force ...
, and the abandonment of invasion plans (correctly reported by both SIS and the
Bletchley Park Bletchley Park is an English country house and Bletchley Park estate, estate in Bletchley, Milton Keynes (Buckinghamshire), that became the principal centre of Allies of World War II, Allied World War II cryptography, code-breaking during the S ...
Ultra Ultra may refer to: Science and technology * Ultra (cryptography), the codename for cryptographic intelligence obtained from signal traffic in World War II * Adobe Ultra, a vector-keying application * Sun Ultra series, a brand of computer work ...
project), the spy scare eased, and the internment policy was gradually reversed. This eased pressure on MI5, and allowed it to concentrate on its major wartime success, the so-called 'double-cross' system. This was a system based on an internal memo drafted by an MI5 officer in 1936, which criticised the long-standing policy of arresting and sending to trial all enemy agents discovered by MI5. Several had offered to defect to Britain when captured; before 1939, such requests were invariably turned down. The memo advocated attempting to 'turn' captured agents wherever possible, and use them to mislead enemy intelligence agencies. This suggestion was turned into a massive and well-tuned system of deception during the Second World War. Beginning with the capture of an agent named
Arthur Owens Arthur Graham Owens, later known as Arthur Graham White (14 April 1899 – 24 December 1957), was a Welsh double agent for the Allies during the Second World War. He was working for MI5 while appearing to the ''Abwehr'' (the German intelligence ...
, codenamed 'Snow', MI5 began to offer enemy agents the chance to avoid prosecution (and thus the possibility of the death penalty) if they would work as British
double-agent In the field of counterintelligence, a double agent is an employee of a secret intelligence service for one country, whose primary purpose is to spy on a target organization of another country, but who is now spying on their own country's organ ...
s. Agents who agreed to this were supervised by MI5 in transmitting bogus 'intelligence' back to the German secret service, the
Abwehr The (German language, German for ''resistance'' or ''defence'', though the word usually means ''counterintelligence'' in a military context) ) was the German military intelligence , military-intelligence service for the ''Reichswehr'' and the ...
. This necessitated a large-scale organisational effort, since the information had to appear valuable but actually be misleading. A high-level committee, the Wireless Board, was formed to provide this information. The day-to-day operation was delegated to a sub-committee, the Twenty Committee (so called because the Roman numerals for twenty, XX, form a double cross). The system was extraordinarily successful. A post-war analysis of German intelligence records found that of the 115 or so agents targeted against Britain during the war, all but one (who committed suicide) had been successfully identified and caught, with several 'turned' to become double agents. The system played a major part in the massive campaign of deception which preceded the
D-Day The Normandy landings were the landing operations and associated airborne operations on 6 June 1944 of the Allied invasion of Normandy in Operation Overlord during the Second World War. Codenamed Operation Neptune and often referred to as ...
landings, designed to give the Germans a false impression of the location and timings of the landings (see
Operation Fortitude Operation Fortitude was a military deception operation by the Allied nations as part of Operation Bodyguard, an overall deception strategy during the buildup to the 1944 Normandy landings. Fortitude was divided into two subplans, North and So ...
). While the double-cross work dealt with enemy agents sent into Britain, a smaller-scale operation run by
Victor Rothschild Nathaniel Mayer Victor Rothschild, 3rd Baron Rothschild, (31 October 1910 – 20 March 1990), was a British scientist, intelligence officer during World War II, and later a senior executive with Royal Dutch Shell and N M Rothschild & Sons, and ...
targeted British citizens who wanted to help Germany. The '
Fifth Column A fifth column is a group of people who undermine a larger group or nation from within, usually in favor of an enemy group or another nation. The activities of a fifth column can be overt or clandestine. Forces gathered in secret can mobilize ...
' operation saw an MI5 officer,
Eric Roberts Eric Anthony Roberts (born April 18, 1956) is an American actor. He has amassed more than 700 film and television credits since his debut in 1978, making him one of the most prolific English-speaking screen actors of all time. Roberts' career ...
, masquerade as the Gestapo's man in London, encouraging Nazi sympathisers to pass him information about people who would be willing to help Germany in the event of invasion. When his recruits began bringing in intelligence, he promised to pass that on to Berlin. The operation was deeply controversial within MI5, with opponents arguing that it amounted to entrapment. By the end of the war, Roberts had identified around 500 people. But MI5 decided not to prosecute, and instead covered the work up, even giving some of Roberts' recruits Nazi medals. They were never told the truth. All foreigners entering the country were processed at the London Reception Centre (LRC) at the
Royal Victoria Patriotic Building The Royal Victoria Patriotic Building is a large Victorian building in a Gothic Revival architecture, Gothic Revival style combining Scottish Baronial architecture, Scottish Baronial and French Châteauesque. It is located off Trinity Road in W ...
, which was operated by MI5 subsection B1D; 30,000 were inspected at LRC. Captured enemy agents were taken to
Camp 020 Camp 020 at Latchmere House in Ham, Surrey (now in the London Borough of Richmond upon Thames), was a British interrogation centre for captured German agents during the Second World War. It was run by Lieutenant Colonel Robin "Tin Eye" Stephen ...
,
Latchmere House Latchmere House is a building and grounds southeast of Ham Common in Ham, in the London Borough of Richmond upon Thames, in south west London, England. The southern part of the site lies in the Royal Borough of Kingston upon Thames. Originall ...
, for interrogation. This was commanded by Colonel Robin Stephens. There was a reserve camp, Camp 020R, at
Huntercombe Huntercombe is an area of Cippenham in Slough in the English historic county of Buckinghamshire, although it was administered as part of Berkshire between 1974 and 1996. It adjoins Burnham in Buckinghamshire. The district is well known to res ...
, which was used mainly for long term detention of prisoners. It is believed that two MI5 officers participated in "a gentle interrogation" given to the senior Nazi
Heinrich Himmler Heinrich Luitpold Himmler (; 7 October 1900 â€“ 23 May 1945) was a German Nazism, Nazi politician and military leader who was the 4th of the (Protection Squadron; SS), a leading member of the Nazi Party, and one of the most powerful p ...
after his arrest at a military checkpoint in the northern German village of Bremervörde in May 1945. Himmler subsequently killed himself during a medical examination by a British officer by means of a cyanide capsule that he had concealed in his mouth. One of the MI5 officers, Sidney Henry Noakes of the Intelligence Corps, was subsequently given permission to keep Himmler's
brace Brace (formerly known as ''Brace For War'') was an Australian mixed martial arts (MMA) promotion. Brace was founded in 2005 by Kya Pate. In an interview with MMA Kanvas Kya Pate detailed what it is like to be the promoter of Australian MMA. Si ...
s and the forged identity document that had led to his arrest.


Post-Second World War

The Prime Minister's personal responsibility for the service was delegated to the
Home Secretary The secretary of state for the Home Department, more commonly known as the home secretary, is a senior minister of the Crown in the Government of the United Kingdom and the head of the Home Office. The position is a Great Office of State, maki ...
David Maxwell-Fyfe David Patrick Maxwell Fyfe, 1st Earl of Kilmuir, (29 May 1900 – 27 January 1967), known as Sir David Maxwell Fyfe from 1942 to 1954 and as Viscount Kilmuir from 1954 to 1962, was a British Conservative politician, lawyer and judge who combi ...
in 1952, with a directive issued by the Home Secretary setting out the role and objectives of the Director General. The service was subsequently placed on a statutory basis in 1989 with the introduction of the Security Service Act. This was the first government acknowledgement of the existence of the service. The post-war period was a difficult time for the service, with a significant change in the threat as the
Cold War The Cold War was a period of global Geopolitics, geopolitical rivalry between the United States (US) and the Soviet Union (USSR) and their respective allies, the capitalist Western Bloc and communist Eastern Bloc, which lasted from 1947 unt ...
began, being challenged by an extremely active
KGB The Committee for State Security (, ), abbreviated as KGB (, ; ) was the main security agency of the Soviet Union from 1954 to 1991. It was the direct successor of preceding Soviet secret police agencies including the Cheka, Joint State Polit ...
, and increasing incidence of the Northern Ireland conflict, and international
terrorism Terrorism, in its broadest sense, is the use of violence against non-combatants to achieve political or ideological aims. The term is used in this regard primarily to refer to intentional violence during peacetime or in the context of war aga ...
. Whilst little has yet been released regarding the successes of the service, there have been a number of intelligence failures which have created embarrassment for both the service and the government. For instance, in 1983, one of its officers,
Michael Bettaney Michael John Bettaney (13 February 1950 – 16 August 2018),"Report of the Security Commission, May 1985", Cmnd 9514, HMSO. also known as Michael Malkin, was a British intelligence officer who worked in the counter-espionage branch of the Secur ...
, was caught trying to sell information to the KGB. He was subsequently convicted of espionage. Following the
Michael Bettaney Michael John Bettaney (13 February 1950 – 16 August 2018),"Report of the Security Commission, May 1985", Cmnd 9514, HMSO. also known as Michael Malkin, was a British intelligence officer who worked in the counter-espionage branch of the Secur ...
case,
Philip Woodfield Sir Philip John Woodfield, (10 August 1923 – 17 September 2000) was a British civil servant. Life and career Woodfield was born in Dulwich, south-east London, and attended Alleyn's School, Dulwich. He was commissioned in the Royal Artillery ...
was appointed as a staff counsellor for the security and intelligence services. His role was to be available to be consulted by any member or former member of the security and intelligence services who had "anxieties relating to the work of his or her service" that it had not been possible to allay through the ordinary processes of management-staff relations, including proposals for publications. The service was instrumental in breaking up a large
Soviet The Union of Soviet Socialist Republics. (USSR), commonly known as the Soviet Union, was a List of former transcontinental countries#Since 1700, transcontinental country that spanned much of Eurasia from 1922 until Dissolution of the Soviet ...
spy ring at the start of the 1970s, with 105 Soviet embassy staff known or suspected to be involved in intelligence activities being expelled from the country in 1971. One episode involving MI5 and the
BBC The British Broadcasting Corporation (BBC) is a British public service broadcaster headquartered at Broadcasting House in London, England. Originally established in 1922 as the British Broadcasting Company, it evolved into its current sta ...
came to light in the mid-1980s. MI5 officer Ronnie Stonham had an office in the BBC, and took part in vetting procedures. Controversy arose when it was alleged that the service was monitoring
trade union A trade union (British English) or labor union (American English), often simply referred to as a union, is an organization of workers whose purpose is to maintain or improve the conditions of their employment, such as attaining better wages ...
s and left-wing politicians. A file was kept on Labour Prime Minister
Harold Wilson James Harold Wilson, Baron Wilson of Rievaulx (11 March 1916 – 23 May 1995) was a British statesman and Labour Party (UK), Labour Party politician who twice served as Prime Minister of the United Kingdom, from 1964 to 1970 and again from 197 ...
from 1945, when he became a Member of Parliament (MP), although the agency's official historian, Christopher Andrew maintains that his fears of MI5 conspiracies and bugging were unfounded. As Home Secretary, the Labour MP
Jack Straw John Whitaker Straw (born 3 August 1946) is a British politician who served in the Cabinet from 1997 to 2010 under the Labour governments of Tony Blair and Gordon Brown. He held two of the traditional Great Offices of State, as Home Secretar ...
discovered the existence of his own file dating from his days as a student radical. One of the most significant and far-reaching failures was an inability to conclusively detect and apprehend the '
Cambridge Five The Cambridge Five was a ring of spies in the United Kingdom that passed information to the Soviet Union during the Second World War and the Cold War and was active from the 1930s until at least the early 1950s. None of the known members were e ...
' spy ring, which had formed in the inter-war years, and achieved great success in penetrating the government, and the intelligence agencies themselves. Related to this failure were suggestions of a high-level penetration within the service, Peter Wright (especially in his controversial book ''
Spycatcher ''Spycatcher: The Candid Autobiography of a Senior Intelligence Officer'' (1987) is a memoir written by Peter Wright, former MI5 officer and assistant director, and co-author Paul Greengrass. Wright drew on his experiences and research into ...
'') and others believing that evidence implicated the former Director General,
Roger Hollis Sir Roger Henry Hollis (2 December 1905 – 26 October 1973) was a British intelligence officer who served with MI5 from 1938 to 1965. He was Director General of MI5 from 1956 to 1965. Some commentators, including the journalist Chapman Pinc ...
, or his deputy Graham Mitchell. The
Trend A fad, trend, or craze is any form of collective behavior that develops within a culture, a generation, or social group in which a group of people enthusiastically follow an impulse for a short time period. Fads are objects or behaviors th ...
inquiry of 1974 found the case unproven of that accusation, and that view was later supported by the former KGB officer
Oleg Gordievsky Oleg Antonovich Gordievsky (; 10 October 1938 – 4 March 2025) was a colonel of the KGB who became KGB resident-designate (''rezident'') and bureau chief in London. Gordievsky was a double agent, providing information to the British Secret ...
. Another spy ring, the
Portland spy ring The Portland spy ring was an spy ring, espionage group active in the UK between 1953 and 1961. It comprised five people who obtained classified research documents from the Admiralty Underwater Weapons Establishment (AUWE) on the Isle of Port ...
, exposed after a tip-off by Soviet defector
Michael Goleniewski Michał Franciszek Goleniewski, also known as 'SNIPER' and 'LAVINIA' (16 August 1922 – 12 July 1993), was a Polish spy and military officer. He was an officer in the People's Republic of Poland, Polish People's Republic's Ministry of Public ...
, led to an extensive MI5 surveillance operation. In 1991, MI5 revealed its head publicly for the first time and declassified some information, "such as the number of its employees and its organizational structure." There have been strong accusations levelled against MI5 for having failed in its obligation to provide care for former police agents who had infiltrated the
Provisional IRA The Provisional Irish Republican Army (Provisional IRA), officially known as the Irish Republican Army (IRA; ) and informally known as the Provos, was an Irish republican paramilitary force that sought to end British rule in Northern Ireland ...
during
the Troubles The Troubles () were an ethno-nationalist conflict in Northern Ireland that lasted for about 30 years from the late 1960s to 1998. Also known internationally as the Northern Ireland conflict, it began in the late 1960s and is usually deemed t ...
. The two most notable of the agents, Martin McGartland and Raymond Gilmour, went on to reside in England using false identities, and in 2012, launched test cases against the agency. Both men claimed to journalist Liam Clarke in the ''Belfast Telegraph'' that they were abandoned by MI5 and were "left high and dry despite severe health problems as a result of their work and lavish promises of life-time care from their former Intelligence bosses". Both men suffer from
post-traumatic stress disorder Post-traumatic stress disorder (PTSD) is a mental disorder that develops from experiencing a Psychological trauma, traumatic event, such as sexual assault, domestic violence, child abuse, warfare and its associated traumas, natural disaster ...
(PTSD). Following the
United States invasion of Afghanistan Shortly after the September 11 attacks in 2001, the United States declared the war on terror and subsequently led a multinational military operation against Taliban-ruled Afghanistan. The stated goal was to dismantle al-Qaeda, which had exe ...
, on 9 January 2002, the first MI5 staff arrived at
Bagram Bagram (; Pashto/) is a town and seat in Bagram District in Parwan Province of Afghanistan, about 60 kilometers north of the capital Kabul. It is the site of an ancient city located at the junction of the Ghorband and Panjshir Valley, near t ...
. On 12 January 2002, following a report by an
MI6 The Secret Intelligence Service (SIS), commonly known as MI6 ( Military Intelligence, Section 6), is the foreign intelligence service of the United Kingdom, tasked mainly with the covert overseas collection and analysis of human intelligenc ...
officer that a detainee appeared to have been mistreated before, an MI6 officer was sent instructions that were copied to all MI5 and MI6 staff in Afghanistan about how to deal with concerns over mistreatment, referring to signs of abuse: 'Given that they are not within our custody or control, the law does not require you to intervene to protect this'. It went on to say that the Americans had to understand that the UK did not condone such mistreatment, and that a complaint should be made to a senior US official if there was any coercion by the US in conjunction with an MI6 interview.


Counter-terrorism

The end of the
Cold War The Cold War was a period of global Geopolitics, geopolitical rivalry between the United States (US) and the Soviet Union (USSR) and their respective allies, the capitalist Western Bloc and communist Eastern Bloc, which lasted from 1947 unt ...
resulted in a change in emphasis for the operations of the service, assuming responsibility for the investigation of all
Irish republican Irish republicanism () is the political movement for an Irish republic, void of any British rule. Throughout its centuries of existence, it has encompassed various tactics and identities, simultaneously elective and militant and has been both w ...
activity within Britain, and increasing the effort countering other forms of terrorism, particularly in more recent years the more widespread threat of
Islamic extremism Islamic extremism refers to extremist beliefs, behaviors and ideologies adhered to by some Muslims within Islam. The term 'Islamic extremism' is contentious, encompassing a spectrum of definitions, ranging from academic interpretations of Is ...
. Whilst the British security forces in
Northern Ireland Northern Ireland ( ; ) is a Countries of the United Kingdom, part of the United Kingdom in the north-east of the island of Ireland. It has been #Descriptions, variously described as a country, province or region. Northern Ireland shares Repub ...
have provided support in the countering of both republican and
loyalist Loyalism, in the United Kingdom, its overseas territories and its former colonies, refers to the allegiance to the British crown or the United Kingdom. In North America, the most common usage of the term refers to loyalty to the British Cr ...
paramilitary A paramilitary is a military that is not a part of a country's official or legitimate armed forces. The Oxford English Dictionary traces the use of the term "paramilitary" as far back as 1934. Overview Though a paramilitary is, by definiti ...
groups since the early 1970s, republican sources have often accused these forces of
collusion Collusion is a deceitful agreement or secret cooperation between two or more parties to limit open competition by deceiving, misleading or defrauding others of their legal right. Collusion is not always considered illegal. It can be used to att ...
with loyalists. In 2006, an Irish government committee inquiry found that there was widespread collusion between British security forces and loyalist terrorists in the 1970s, which resulted in eighteen deaths. In 2012, a document based review by
Sir Desmond de Silva Sir George Desmond Lorenz de Silva, (13 December 1939 – 2 June 2018) was a British criminal law barrister and international lawyer who served as the United Nations Chief War Crimes Prosecutor in Sierra Leone. Early life Desmond de Silva was ...
QC into the 1989 murder of Belfast solicitor
Pat Finucane Patrick Finucane (; 21 March 1949 – 12 February 1989) was an Irish international human rights lawyer, most notable for his challenge of the British government in human rights cases on behalf of Irish Republican Army (IRA) hunger strikers suc ...
found that MI5 had colluded with the
Ulster Defence Association The Ulster Defence Association (UDA) is an Ulster loyalist paramilitary group in Northern Ireland. It was formed in September 1971 as an umbrella group for various loyalist groups and undertook an armed campaign of almost 24 years as one of t ...
(UDA). The review disclosed that MI5 assessments of UDA intelligence consistently noted that the majority came from MI5 sources, with an assessment in 1985 finding 85% came from MI5.
Prime Minister A prime minister or chief of cabinet is the head of the cabinet and the leader of the ministers in the executive branch of government, often in a parliamentary or semi-presidential system. A prime minister is not the head of state, but r ...
David Cameron David William Donald Cameron, Baron Cameron of Chipping Norton (born 9 October 1966) is a British politician who served as Prime Minister of the United Kingdom from 2010 to 2016. Until 2015, he led the first coalition government in the UK s ...
accepted the findings, and apologised on behalf of the British government, and acknowledged significant levels of collusion with Loyalists in its state agencies. On 10 October 2007, the lead responsibility for national security intelligence in Northern Ireland returned to the Security Service from the
Police Service of Northern Ireland The Police Service of Northern Ireland (PSNI; ; Ulster-Scots: '), is the police service responsible for law enforcement and the prevention of crime within Northern Ireland. It is the successor to the Royal Ulster Constabulary (RUC) after it ...
(PSNI), that had been devolved in 1976 to the
Royal Ulster Constabulary The Royal Ulster Constabulary (RUC) was the police force in Northern Ireland from 1922 to 2001. It was founded on 1 June 1922 as a successor to the Royal Irish Constabulary (RIC) Richard Doherty, ''The Thin Green Line – The History of the ...
(RUC) during Ulsterisation. During April 2010, the
Real IRA The Real Irish Republican Army, or Real IRA (RIRA), was a Dissident republican, dissident Irish republican paramilitary group that aimed to bring about a United Ireland. It was formed in 1997 following a split in the Provisional Irish Republica ...
detonated a 120 lb
car bomb A car bomb, bus bomb, van bomb, lorry bomb, or truck bomb, also known as a vehicle-borne improvised explosive device (VBIED), is an improvised explosive device designed to be detonated in an automobile or other vehicles. Car bombs can be roug ...
outside Palace Barracks in
County Down County Down () is one of the six counties of Northern Ireland, one of the nine counties of Ulster and one of the traditional thirty-two counties of Ireland. It covers an area of and has a population of 552,261. It borders County Antrim to the ...
, which is the headquarters of MI5 in Northern Ireland and also home to the 2nd Battalion
The Mercian Regiment The Mercian Regiment (Cheshire, Worcesters and Foresters, and Staffords) is an infantry regiment of the British Army, which is recruited from five of the counties that formed the ancient kingdom of Mercia. Known as 'The Heart of England's Infant ...
. MI5 is understood to have a close working relationship with the
Republic of Ireland Ireland ( ), also known as the Republic of Ireland (), is a country in Northwestern Europe, north-western Europe consisting of 26 of the 32 Counties of Ireland, counties of the island of Ireland, with a population of about 5.4 million. ...
's
Special Detective Unit The Special Detective Unit (SDU) () is the main domestic security agency of the ''Garda Síochána'', the national police force of Ireland, under the aegis of the Crime & Security Branch (CSB). It is the primary counter-terrorism and counter-es ...
(SDU), the counter-terrorism and counter-intelligence section of the
Garda Síochána (; meaning "the Guardian(s) of the Peace") is the national police and security service of Republic of Ireland, Ireland. It is more commonly referred to as the Gardaí (; "Guardians") or "the Guards". The service is headed by the Garda Commissio ...
(national police), particularly with regards to threats from
dissident republican Dissident republicans () are Irish republicans who do not support the Northern Ireland peace process. The peace agreements followed a 30-year conflict known as the Troubles, in which over 3,500 people were killed and 47,500 injured, and in whi ...
terrorism and
Islamic terrorism Islamic terrorism (also known as Islamist terrorism, radical Islamic terrorism, or jihadist terrorism) refers to terrorist acts carried out by fundamentalist militant Islamists and Islamic extremists. Since at least the 1990s, Islami ...
. Executive liaison groups enable MI5 to safely share secret, sensitive, and often raw intelligence with the police, on which decisions can be made about how best to gather evidence and prosecute suspects in the courts. Each organisation works in partnership throughout the investigation, but MI5 retain the lead for collecting, assessing and exploiting intelligence. The police take lead responsibility for gathering evidence, obtaining arrests, and preventing risks to the public.


Serious crime

In 1996, legislation formalised the extension of the Security Service's statutory remit to include supporting the law enforcement agencies in their work against serious crime. Tasking was reactive, acting at the request of law enforcement bodies such as the
National Criminal Intelligence Service The National Criminal Intelligence Service (NCIS) was a United Kingdom Law enforcement in the United Kingdom, policing agency. Following the Police and Criminal Justice Act 2001, NCIS returned to direct funding by the Home Office in 2002 and was a ...
(NCIS), for whom MI5 officers performed electronic surveillance and eavesdropping duties during Operation Trinity. This role has subsequently been passed to the
Serious Organised Crime Agency The Serious Organised Crime Agency (SOCA) was a non-departmental public body of the Government of the United Kingdom which existed from 1 April 2006 until 7 October 2013. SOCA was a national law enforcement agency with Home Office sponsorship, e ...
(SOCA) and then the
National Crime Agency The National Crime Agency (NCA) is a Law enforcement agency#natlea, national law enforcement agency in the United Kingdom. It is the UK's lead agency against organised crime; Human trafficking, human, Arms trafficking, weapon and Illegal drug t ...
(NCA).


Surveillance

In 2001, after the
September 11 attacks The September 11 attacks, also known as 9/11, were four coordinated Islamist terrorist suicide attacks by al-Qaeda against the United States in 2001. Nineteen terrorists hijacked four commercial airliners, crashing the first two into ...
in the US, MI5 started collecting bulk telephone communications data under a little understood general power of the
Telecommunications Act 1984 The Telecommunications Act 1984 (c. 12) is an Act of the Parliament of the United Kingdom. The rules for the industry are now contained in the Communications Act 2003. Provisions The provisions of the act included the following: * Privatising ...
(instead of the
Regulation of Investigatory Powers Act 2000 The Regulation of Investigatory Powers Act 2000 (citation of United Kingdom legislation, c. 23) (RIP or RIPA) is an Act of parliament, Act of the Parliament of the United Kingdom, regulating the powers of public bodies to carry out surveillanc ...
which would have brought independent oversight and regulation). This was kept secret until announced by the
Home Secretary The secretary of state for the Home Department, more commonly known as the home secretary, is a senior minister of the Crown in the Government of the United Kingdom and the head of the Home Office. The position is a Great Office of State, maki ...
in 2015. This power was replaced by the
Investigatory Powers Act 2016 The Investigatory Powers Act 2016 (c. 25) (nicknamed the Snoopers' Charter) is an Act of the Parliament of the United Kingdom which received royal assent on 29 November 2016. Its different parts came into force on various dates from 30 December ...
which introduced new surveillance powers overseen by the Investigatory Powers Commission (IPC) it introduces. In July 2006, parliamentarian
Norman Baker Norman John Baker (born 26 July 1957) is a Liberal Democrats (UK), Liberal Democrat politician in the United Kingdom who was the Member of Parliament (United Kingdom), Member of Parliament (MP) for Lewes (UK Parliament constituency), Lewes in ...
accused the British Government of "hoarding information about people who pose no danger to this country", after it emerged that MI5 holds secret files on 272,000 individuals, equivalent to one in 160 adults. It had previously been revealed that a '
traffic light Traffic lights, traffic signals, or stoplights – also known as robots in South Africa, Zambia, and Namibia – are signaling devices positioned at intersection (road), road intersections, pedestrian crossings, and other locations in order t ...
' system operates: *Green: active; about 10% of files *Amber: enquiries prohibited, further information may be added; about 46% of files *Red: enquiries prohibited, substantial information may not be added; about 44% of files.


Participation of MI5 officers in criminal activity

In March 2018, the government acknowledged that MI5 officers are allowed to authorise agents to commit criminal activity in the UK. Maya Foa, the director of Reprieve, said: "After a seven-month legal battle, the prime minister has finally been forced to publish her secret order, but we are a long way from having transparency. The public and parliament are still being denied the guidance that says when British spies can commit criminal offences, and how far they can go. Authorised criminality is the most intrusive power a state can wield. Theresa May must publish this guidance without delay". In November 2019, four
human rights organisation A human rights group, or human rights organization, is a non-governmental organization which advocates for human rights through identification of their violation, collecting incident data, its analysis and publication, promotion of public awareness ...
s claimed that the UK government has a policy dating from the 1990s to allow MI5 officers to authorise agents or informers to participate in crime, and to immunise them against prosecution for criminal actions. The organisations said the policy allowed MI5 officers to authorise agents and informers to participate in criminal activities that protected national security or the economic well-being of the UK. The organisations took the UK government to the
Investigatory Powers Tribunal The Investigatory Powers Tribunal (IPT) is a first-instance tribunal and superior court of record in the United Kingdom. It is primarily an inquisitorial court. It hears complaints about surveillance by public bodies, primarily the intelligen ...
, seeking to have it declare the policy illegal, and to issue an injunction against further 'unlawful conduct'. In December 2019, the tribunal dismissed the request of the human rights organisations in a 3-to-2 decision. The potential criminal activities include murder, kidnap, and torture, according to a
Bloomberg Bloomberg may refer to: People * Daniel J. Bloomberg (1905–1984), audio engineer * Georgina Bloomberg (born 1983), professional equestrian * Michael Bloomberg (born 1942), American businessman and founder of Bloomberg L.P.; politician a ...
report.


Allegations of collusion in torture

In October 2020, Rangzieb Ahmed brought a civil claim against MI5, alleging that Pakistan's
Inter-Services Intelligence The Inter-Services Intelligence (ISI) is the premier Pakistani Intelligence community, intelligence agency of Pakistan. It is responsible for gathering, processing, and analyzing any information from around the world that is deemed relevant t ...
agency had arrested him in 2006, and that MI5 had colluded in torture by submitting questions which were put to him under torture in Pakistan. This claim was rejected by the High Court on 16 December 2020.


Domestic abuse scandal

In May 2022, the BBC reported on an unnamed MI5 agent, 'X', domestically abusing his partner, despite the British government's attempts to block this. BBC journalists subsequently discovered that MI5 lied to courts, suggesting that the organisation was unaware of X's behaviour, including his far-right extremist views. An ongoing High Court case began in June 2025, with MI5 accepting that X's status should no longer be protected, after previously neither confirming nor denying his role as an agent.


Buildings

MI5 was based at Watergate House in the
Strand Strand or The Strand may refer to: Topography *The flat area of land bordering a body of water, a: ** Beach ** Shoreline * Strand swamp, a type of swamp habitat in Florida Places Africa * Strand, Western Cape, a seaside town in South Africa * ...
from 1912 until 1916, when it moved to larger facilities at 16 Charles Street for the remaining years of the
First World War World War I or the First World War (28 July 1914 – 11 November 1918), also known as the Great War, was a World war, global conflict between two coalitions: the Allies of World War I, Allies (or Entente) and the Central Powers. Fighting to ...
. After the First World War, it relocated to smaller premises at 73–75
Queen's Gate Queen's Gate is a street in South Kensington, London, England. It runs south from Kensington Gardens' Queen's Gate (the edge of which gardens are here followed by Kensington Road) to Old Brompton Road, intersecting Cromwell Road. The street i ...
in 1919, and then moved to 35
Cromwell Road Cromwell Road is a major London road in the Royal Borough of Kensington and Chelsea, designated as part of the A4 road (Great Britain), A4. It was created in the 19th century and is said to be named after Richard Cromwell, son of Oliver Cromwel ...
in 1929, before transferring to the top floor of the South Block of
Thames House Thames House is an office building in Millbank, London, on the north bank of the River Thames adjacent to Lambeth Bridge. Originally used as offices by Imperial Chemical Industries (ICI), it has served as the headquarters of the United Kingdom's ...
on
Millbank Millbank is an area of central London in the City of Westminster. Millbank is located by the River Thames, east of Pimlico and south of Westminster. Millbank is known as the location of major government offices, Burberry headquarters, the Mill ...
in 1934. The Service spent the first year of the
Second World War World War II or the Second World War (1 September 1939 – 2 September 1945) was a World war, global conflict between two coalitions: the Allies of World War II, Allies and the Axis powers. World War II by country, Nearly all of the wo ...
at
Wormwood Scrubs Wormwood Scrubs, known locally as The Scrubs (or simply Scrubs), is an open space in Old Oak Common located in the north-eastern corner of the London Borough of Hammersmith and Fulham in west London. It is the largest open space in the borough ...
, before moving to
Blenheim Palace Blenheim Palace ( ) is a country house in Woodstock, Oxfordshire, England. It is the seat of the Dukes of Marlborough. Originally called Blenheim Castle, it has been known as Blenheim Palace since the 19th century. One of England's larg ...
, Oxfordshire, in 1940. After the Second World War, MI5 was based at
Leconfield House Leconfield House is a building in Mayfair, London. It was the headquarters of the Security Service (MI5) from 1945 to 1976. History Early history The site at the junction of South Audley Street and Curzon Street was occupied in the second hal ...
(1945–1976), and 140 Gower Street (1976–1994, since demolished), before returning to Thames House in 1994. The national headquarters at Thames House draws together personnel from a number of locations into a single HQ facility: Thames House also houses the
Joint Terrorism Analysis Centre The Joint Terrorism Analysis Centre (JTAC) is an all-source intelligence organisation closely related to the United Kingdom Security Service which provides advice to the British government and firms within the Critical National Infrastructure ...
(JTAC), a subordinate organisation to the Security Service; prior to March 2013, Thames House additionally housed the
Northern Ireland Office The Northern Ireland Office (NIO; , Ulster-Scots: ''Norlin Airlann Oaffis'') is a ministerial department of the Government of the United Kingdom. It is responsible for handling Northern Ireland affairs. The NIO is led by the Secretary of S ...
(NIO). The service has offices across the United Kingdom, including a HQ in
Northern Ireland Northern Ireland ( ; ) is a Countries of the United Kingdom, part of the United Kingdom in the north-east of the island of Ireland. It has been #Descriptions, variously described as a country, province or region. Northern Ireland shares Repub ...
. Details of a northern operations centre in
Greater Manchester Greater Manchester is a ceremonial county in North West England. It borders Lancashire to the north, Derbyshire and West Yorkshire to the east, Cheshire to the south, and Merseyside to the west. Its largest settlement is the city of Manchester. ...
were revealed by the firm who built it.


Directors General of the Security Service

*1909–1940: Sir Vernon Kell (born 1873 – d. 1942) *1940–1941:
Oswald Allen Harker Brigadier Oswald Allen Harker CBE (1886–1968), known as Jasper Harker, was Acting Director General of MI5 from 1940 to 1941. Background Oswald Allen Harker was born in Cirencester in 1886, the son of James Allen Harker, a professor at the Roy ...
(born 1886 – d. 1968) *1941–1946: Sir David Petrie (born 1879 – d. 1961) *1946–1953: Sir Percy Sillitoe (born 1888 – d. 1962) *1953–1956:
Dick White Sir Dick Goldsmith White, (20 December 1906 – 21 February 1993) was a British intelligence officer. He was Director General (DG) of MI5 from 1953 to 1956, and Head of the Secret Intelligence Service (MI6) from 1956 to 1968. Early life Whi ...
(born 1906 – d. 1993) *1956–1965:
Roger Hollis Sir Roger Henry Hollis (2 December 1905 – 26 October 1973) was a British intelligence officer who served with MI5 from 1938 to 1965. He was Director General of MI5 from 1956 to 1965. Some commentators, including the journalist Chapman Pinc ...
(born 1905 – d. 1973) *1965–1972:
Martin Furnival Jones Sir Edward Martin Furnival Jones CBE (7 May 1912 – 1 March 1997) was Director General of MI5, the United Kingdom's internal security service, from 1965 until 1972. Career Born in High Barnet and educated at Highgate School, Furnival Jones was ...
(born 1912 – d. 1997) *1972–1979:
Michael Hanley Sir Michael Bowen Hanley KCB (24 February 1918 – 1 January 2001) was Director General (DG) of MI5, the United Kingdom's internal security service, from 1972 to 1978. Career Educated at Sedbergh School and Queen's College, Oxford where he re ...
(born 1918 – d. 2001) *1979–1981: Howard Smith (born 1919 – d. 1996) *1981–1985: John Jones (born 1923 – d. 1998) *1985–1988:
Antony Duff Sir Arthur Antony Duff (25 February 1920 – 13 August 2000) was a senior British diplomat and Director General of MI5. Early life and naval service Duff was born on 25 February 1920, to Admiral Sir Arthur Allen Morison Duff KCB and Margaret ...
(born 1920 – d. 2000) *1988–1992: Patrick Walker (born 1932 - d. 2021) *1992–1996:
Stella Rimington Dame Stella Rimington (born 13 May 1935) is a British author and former Director General of MI5, a position she held from 1992 to 1996. She was the first female DG of MI5, and the first DG whose name was publicised on appointment. In 1993, Rimi ...
(born 1935) *1996–2002:
Stephen Lander Sir Stephen James Lander, KCB (born 1947) is a former chairman of the United Kingdom's Serious Organised Crime Agency (SOCA), who also served as Director General of the British Security Service (MI5) from 1996 to 2002. Career Lander attended ...
(born 1947) *2002–2007:
Eliza Manningham-Buller Elizabeth Lydia Manningham-Buller, Baroness Manningham-Buller (born 14 July 1948) is a retired British intelligence officer. She worked as a teacher for three years before joining MI5, the British internal Security Service. She led the newly c ...
(born 1948) *2007–2013: Jonathan Evans (born 1958) *2013–2020: Andrew Parker (born 1962) * 2020–present:
Ken McCallum Sir Kenneth Douglas McCallum (born 1974) is a British intelligence officer who has been serving as the Director General of MI5 since 2020. Early life and education McCallum was born in Glasgow, Scotland, in 1974. He attended a state school, ...
(born 1974)


Past names

Although the Service is commonly referred to as 'MI5', this was its official name for only thirteen years (1916–1929). However, it is still used as a sub-title on the various pages of the official Security Service website, as well as in their web address (https://www.MI5.gov.uk). *October 1909: founded as the Home Section of the Secret Service Bureau; *April 1914: became a sub-section of the War Office Directorate of Military Operations, section 5 (MO5) — MO5(g); *September 1916: became Military Intelligence section 5 — MI5; *1929: renamed the Defence Security Service; *1931: renamed the Security Service.


Cover name

MI5 has previously used Government Communications Planning Directorate (GCPD) as a cover name when sponsoring research related to drone usage in charging recording devices.


Coat of arms


See also

*
British intelligence agencies The Government of the United Kingdom maintains several intelligence agencies that deal with secret intelligence. These agencies are responsible for collecting, analysing and exploiting foreign and domestic intelligence, providing military intell ...
* Annie Machon – MI5 whistleblower *
Delores Kane Delores Kane (born David Shayler, 24 December 1965) is a former British MI5 officer and a conspiracy theorist. Kane was prosecuted under the Official Secrets Act 1989 for passing secret documents to ''The Mail on Sunday'' in August 1997 that al ...
– MI5 whistleblower *
Club de Berne The Club de Berne (, , CdB) is an intelligence sharing alliance between the intelligence services of the 27 states of the European Union (EU), Norway and Switzerland, named after the city of Bern. It is an institution based on voluntary exchange ...
– a European intelligence sharing forum * Counter Terrorism Policing *
Counter Terrorism Command Counter Terrorism Command (CTC) or SO15 is a Specialist Operations branch within London's Metropolitan Police Service. The Counter Terrorism Command was established as a result of the merging of the Anti-Terrorist Branch (SO13) and Special Br ...
– of London's Metropolitan Police Service *
Joint Terrorism Analysis Centre The Joint Terrorism Analysis Centre (JTAC) is an all-source intelligence organisation closely related to the United Kingdom Security Service which provides advice to the British government and firms within the Critical National Infrastructure ...
(JTAC) *
National Protective Security Authority The National Protective Security Authority (NPSA) is the national technical authority in the United Kingdom for physical and personnel protective security, maintaining expertise in counter terrorism as well as state threats. Description T ...
– child agency of MI5 which provides security advice *
Pat Finucane Patrick Finucane (; 21 March 1949 – 12 February 1989) was an Irish international human rights lawyer, most notable for his challenge of the British government in human rights cases on behalf of Irish Republican Army (IRA) hunger strikers suc ...
– Irish lawyer murdered by Ulster Defence Association members with the collusion of the security service


References


Further reading

* * Published as . * * * * * * * * * * * * * *


External links

*
Records of the Security Service
€”from
The National Archives National archives are the archives of a country. The concept evolved in various nations at the dawn of modernity based on the impact of nationalism upon bureaucratic processes of paperwork retention. Conceptual development From the Middle Ages i ...

UK Intelligence community online
€”from the
Cabinet Office The Cabinet Office is a Departments of the Government of the United Kingdom, ministerial department of the Government of the United Kingdom. It is responsible for supporting the Prime Minister of the United Kingdom, prime minister and Cabinet ...
{{Authority control 1909 establishments in the United Kingdom Domestic intelligence agencies British intelligence agencies Buildings and structures in the City of Westminster Intelligence services of World War II Military units and formations of the United Kingdom in World War II