MI5 (British Security Service)

MI5 (British Security Service)



Best known by its designation MI5, the Security Service is the leading counter-espionage agency working in the United Kingdom. Its functions are somewhat akin to those of the United States Federal Bureau of Investigation, but MI5 places a much greater emphasis on intelligence, and its operatives have no arrest powers. Formed in 1916, MI5 devoted itself to intelligence operations against the Germans in both world wars, and against Communists in the interwar and postwar periods. During the early Cold War, MI5 suffered a number of embarrassments involving Soviet moles in its midst. From the 1970s onward, it devoted increasing attention to terrorist activities, and in the 1990s, attempted to balance its sensitive security functions with an increased concern for openness with the British public.

Wartime successes (1909–45). MI5 grew out of the Secret Service Bureau, created in 1909 to protect the British realm against German infiltrators. At the beginning of World War I, the Home Section of the bureau came under the control of the War Office, which designated it MI5 (the "MI" refers to military intelligence) in 1916. Over the course of the war, MI5 assisted in the arrest of several dozen German operatives in Britain.

Under the direction of Captain Vernon Kell, who served as director-general until 1940, MI5 in the immediate postwar years directed its efforts toward spies associated with the new Communist regime in Russia. It uncovered a major Soviet front operation in 1927, but by the 1930s had begun to focus once again on German infiltration. MI5, led by Sir David Petrie in the war years, apprehended numerous German spies, who were subsequently executed. Also important, it succeeded in turning a number of other Axis operatives, such that the Nazis remained convinced they had an extensive spy network in Britain—although in fact the spies were working against them.

Soviet infiltration (1946–79). The postwar years saw some successes, including Operation Engulf, a program of communications interception directed against the Soviets, French, and Egyptians during the Suez Crisis in 1956. MI5 also captured several Soviet operatives, but its achievements were overshadowed by the uncovering of the Cambridge spy ring, whose members served as Soviet moles while working for the British government. Although neither Donald Maclean nor Kim Philby actually worked for MI5, both were under investigation by the agency when they escaped to the other side of the iron curtain in 1949 and 1963, respectively.

Worse revelations were to come. In 1963 it was discovered that Anthony Blunt, who had worked for MI5 in the war years, was also a Soviet agent. Eventually it became apparent that the Soviets had been infiltrating MI5 for most of the postwar period. The list of suspected Soviet agents included some extremely high officials: director-general Sir Roger Hollis (1956–65) and future director-general Sir Michael Hanley (1972–79). These revelations did little to inspire the trust of American intelligence agencies, which cooperated little with MI5 until after the end of Hanley's tenure.

Focus on terrorism (1979-present). By the 1960s, MI5 had become increasingly concerned with terrorism, both by Palestinian and Northern Irish groups. Revelations of Soviet infiltration continued even into the 1980s, when former MI5 operative Michael Bettaney was convicted of espionage on behalf of the KGB. The spy scandals eventually ended, although not so much because of measures MI5 took to counter infiltration, but because of the Soviet Union's collapse.

During the mid-1980s, MI5 came under intense government scrutiny in the form of an investigation by Britain's Security Commission. The result of this was the appointment of Sir Anthony Duff to the director-general's position, and in 1988 Duff took measures to reform the agency. The Security Service Act of 1989 for the first time conferred legal status on MI5, which in December 1991 signaled a new era of openness by announcing the appointment of Stella Rimington as director-general. Rimington became not only its first female director, but the first MI5 chief named in the media.

In 1993, MI5 further demonstrated its openness by publishing a booklet titled The Security Service, which described MI5's six branches of operation: counter-terrorism, counterespionage, counter-subversion, protective security, security intelligence, and record keeping. Meanwhile, in 1992, MI5 was given chief responsibility for British intelligence efforts against Irish terrorism, and over the next seven years it helped bring about 21 convictions for crimes related to terrorism. An emphasis on counterterrorism continued under the leadership of Stephen Lander, appointed director-general in 1996.



Andrew, Christopher M. Her Majesty's Secret Service: The Making of the British Intelligence Community. New York: Viking, 1986.

Bar-Joseph, Uri. Intelligence Intervention in the Politics of Democratic States: The United States, Israel, and Britain. University Park: Pennsylvania State University Press, 1995.

The Security Service: MI5. London: HMSO, 1993.

West, Nigel. Molehunt: Searching for Soviet Spies in MI5. New York: W. Morrow, 1989.


MI5: The Security Service. < http://www.mi5.gov.uk/ > (April 11, 2003).

United Kingdom Intelligence Agencies. Federation of American Scientists. < http://www.fas.org/irp/world/uk/index.html > (April 11, 2003).


Cambridge University Spy Ring
Engulf, Operation

United Kingdom, Intelligence and Security

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