Secret Intelligence Service

Overview

The Secret Intelligence Service is the United Kingdom's foreign human-intelligence service. It is responsible for the secret collection of foreign intelligence outside the United Kingdom, the conduct of disruption operations abroad, and the cultivation of liaison relationships with allied services. It is popularly known as MI6 — a designation derived from its wartime cover as Section 6 of Military Intelligence — but its formal name is, and has always been, the Secret Intelligence Service.¹

The Service operates under the authority of the Foreign Secretary, is headquartered at Vauxhall Cross on the south bank of the Thames, and is led by a Chief who continues by tradition to be designated "C" in internal correspondence — a usage dating to the founding Chief, Mansfield Cumming. Its existence was not formally acknowledged by the British Government until the Intelligence Services Act 1994.²

History & Origins

The Service was established in October 1909 as the Foreign Section of the Secret Service Bureau, set up at the recommendation of a Committee of Imperial Defence sub-committee chaired by Lord Esher to investigate German espionage in Britain. The Bureau's domestic Home Section developed into the Security Service (MI5); the foreign section, under Commander Sir Mansfield Cumming RN, became MI6/SIS. Cumming served as Chief from 1909 until his death in 1923.³

The Service expanded substantially during the First World War and became the principal British secret intelligence organisation between the wars. It suffered the most severe institutional crisis in its history with the discovery, between 1951 and 1963, of a Soviet penetration extending across the senior ranks of British intelligence and the Foreign Office — the so-called Cambridge Five: Harold "Kim" Philby, Donald Maclean, Guy Burgess, Anthony Blunt (Security Service), and John Cairncross. Philby, who had risen to head the Service's anti-Soviet section, defected to Moscow in 1963.⁴

The Cold War period saw close operational partnership with the United States Central Intelligence Agency, including the joint 1953 Iran operation that overthrew Prime Minister Mohammad Mosaddegh. In the post-Cold War era the Intelligence Services Act 1994 placed the Service on a statutory footing for the first time, established the Intelligence and Security Committee of Parliament, and enabled the construction of the Vauxhall Cross headquarters.⁵

The 2003 Iraq War period saw the Service at the centre of public controversy over the September 2002 government dossier on Iraqi weapons of mass destruction. The Hutton Inquiry (2003–04) and the Butler Review (2004) examined SIS reporting and analytical processes, with the Butler Review concluding that SIS reporting from a small number of sources had been overstated in the dossier and subsequently withdrawn after the war.⁶

Mandate & Jurisdiction

The Service's authorities derive principally from the Intelligence Services Act 1994. Its statutory functions are:

• to obtain and provide information relating to the actions or intentions of persons outside the British Islands;
• to perform other tasks relating to the actions or intentions of such persons;
• to act in the interests of national security, in the interests of the economic well-being of the United Kingdom, or in support of the prevention or detection of serious crime.⁷

Section 7 of the Act provides for ministerial authorisation, on a written basis, of acts outside the British Islands that would otherwise be unlawful — the so-called "James Bond clause." Authorisations require Foreign Secretary approval and are reportable to the Intelligence and Security Committee.

The Service operates exclusively outside the United Kingdom. Domestic intelligence is the responsibility of the Security Service (MI5), and signals intelligence is the responsibility of GCHQ.

Notable Operations

Confirmed Operation Boot / Ajax (1953, Iran). The joint SIS–CIA operation that overthrew Prime Minister Mohammad Mosaddegh after his nationalisation of the Anglo-Iranian Oil Company. The British official history acknowledges SIS's role; the CIA's internal history was released publicly in 2013.⁸

Confirmed Operation Foot (1971). The mass expulsion of 105 Soviet intelligence officers from the United Kingdom in September 1971, on the basis of intelligence including the defection of KGB officer Oleg Lyalin. The expulsion remains the largest single removal of foreign intelligence personnel from a Western country.⁹

Confirmed Falklands War intelligence (1982). SIS, working with GCHQ, supplied a continuous flow of Argentine military intelligence to the Task Force during the South Atlantic conflict. The Franks Committee report of 1983 examined intelligence performance in the lead-up to the Argentine invasion.¹⁰

Confirmed September Dossier (2002). "Iraq's Weapons of Mass Destruction: The Assessment of the British Government," published in September 2002, drew substantially on SIS reporting on Iraqi unconventional-weapons programmes. The Butler Review concluded that source-validation and analytical processes had been deficient and that some SIS reporting was subsequently withdrawn.⁶

Confirmed Litvinenko (2006) and Salisbury (2018). UK government attribution of the November 2006 polonium-210 poisoning of Alexander Litvinenko in London to the Russian state, supported by the public inquiry under Sir Robert Owen, and the March 2018 nerve-agent poisoning of Sergei and Yulia Skripal in Salisbury, attributed by the UK government to officers of the Russian GRU's Unit 29155, are the two most prominent recent public-record cases involving the Service's counter-intelligence and attribution work.¹¹

Controversies & Abuses

Confirmed The Cambridge Five. The penetration of British intelligence by Soviet agents recruited at Cambridge in the 1930s remains the most consequential intelligence failure in the Service's history. Philby's career trajectory — to senior counter-intelligence positions and a posting to Washington — and the prolonged delay in his identification became the institutional subject of decades of internal review.⁴

Confirmed Detainee mistreatment in the post-2001 period. The Intelligence and Security Committee's 2018 reports on Detainee Mistreatment and Rendition identified cases in which SIS officers had supplied questions to be asked of detainees held by the United States and other partners under conditions involving documented mistreatment. The Committee concluded that institutional understanding of the law and policy on rendition and mistreatment had been inadequate.¹²

Alleged Specific covert actions. Multiple reputable secondary works — including Stephen Dorril's MI6 and Keith Jeffery's authorised history covering the period to 1949 — describe operations on which the Service has not commented publicly. Jeffery's MI6: The History of the Secret Intelligence Service 1909–1949 is the only authorised history; the post-1949 record remains largely closed.¹³

Notable Figures

• Captain Sir Mansfield Cumming RN — First Chief, 1909–1923. The original "C."
• Sir Stewart Menzies — Chief 1939–1952. Bletchley Park era and early Cold War.
• Harold "Kim" Philby — Headed the Service's anti-Soviet section in the late 1940s; defected to Moscow in 1963.
• Sir John Sawers — Chief 2009–2014. First Chief to deliver a public speech in the post.
• Sir Alex Younger — Chief 2014–2020.
• Sir Richard Moore — Chief 2020–present. Active on social media as @ChiefMI6 — itself a notable departure from institutional tradition.¹⁴

Oversight & Accountability

The Service is subject to oversight by the Foreign Secretary as the responsible minister; the Intelligence and Security Committee of Parliament, established in its current statutory form by the Justice and Security Act 2013; the Investigatory Powers Commissioner and the Investigatory Powers Tribunal; and the National Security Adviser within the Cabinet Office. Section 7 authorisations require ministerial approval and are reportable to the ISC.

The Investigatory Powers Act 2016 placed the Service's bulk-collection and equipment-interference powers on a more detailed statutory footing, with judicial commissioner approval required for the most intrusive warrants under the "double lock" mechanism.¹⁵

Sources & Further Reading

1. Intelligence Services Act 1994, c. 13, sections 1–2; SIS, "About SIS," sis.gov.uk.
2. Intelligence and Security Committee of Parliament, Annual Reports; Keith Jeffery, MI6: The History of the Secret Intelligence Service, 1909–1949 (Bloomsbury, 2010).
3. Christopher Andrew, Secret Service: The Making of the British Intelligence Community (Heinemann, 1985); Jeffery, MI6, chapters 1–4.
4. Christopher Andrew and Vasili Mitrokhin, The Sword and the Shield: The Mitrokhin Archive and the Secret History of the KGB (Basic Books, 1999); Ben Macintyre, A Spy Among Friends: Kim Philby and the Great Betrayal (Crown, 2014).
5. Intelligence Services Act 1994; Stephen Dorril, MI6: Inside the Covert World of Her Majesty's Secret Intelligence Service (Free Press, 2000).
6. The Right Honourable The Lord Butler of Brockwell, Review of Intelligence on Weapons of Mass Destruction, HC 898, 14 July 2004.
7. Intelligence Services Act 1994, sections 1, 7.
8. National Security Archive, "CIA Confirms Role in 1953 Iran Coup," August 2013; Stephen Dorril, MI6, chapter 30.
9. Christopher Andrew, The Defence of the Realm: The Authorized History of MI5 (Allen Lane, 2009), section on Operation FOOT.
10. Lord Franks, Falkland Islands Review: Report of a Committee of Privy Counsellors, Cmnd. 8787, January 1983.
11. Sir Robert Owen, The Litvinenko Inquiry: Report into the Death of Alexander Litvinenko, HC 695, 21 January 2016; UK Government statement on the Salisbury attack, 14 March 2018; Bellingcat, "Skripal Poisoning Suspects" investigation series, 2018–2019.
12. Intelligence and Security Committee of Parliament, Detainee Mistreatment and Rendition: 2001–2010, HC 1113, 28 June 2018; Detainee Mistreatment and Rendition: Current Issues, HC 1114, 28 June 2018.
13. Jeffery, MI6, op. cit.; Dorril, MI6, op. cit.
14. "MI6 chief Richard Moore opens Twitter account in unprecedented step," The Times, 14 October 2020.
15. Investigatory Powers Act 2016, c. 25; Investigatory Powers Commissioner's Office, Annual Reports.