Origins Organised intelligence collection and planning for the
Government of the United Kingdom and the
British Empire was established during the 19th century. The
War Office, responsible for the administration of the
British Army, formed the Intelligence Branch in 1873, which became the
Directorate of Military Intelligence. The
Admiralty, responsible for command of the
Royal Navy, formed the Foreign Intelligence Committee in 1882, which evolved into the
Naval Intelligence Department (NID) in 1887. The
Committee of Imperial Defence, established in 1902, was responsible for research, and some co-ordination, on issues of
military strategy. The Secret Service Bureau was founded in 1909 as a joint initiative of the Admiralty and the War Office to control secret intelligence operations in the UK and overseas, particularly concentrating on the activities of the
Imperial German government. The Bureau operated alongside but independently of the military. It was split into naval and army sections which, over time, specialised in foreign espionage and internal counter-espionage activities respectively. This specialisation, formalised before 1914, was a result of the Admiralty intelligence requirements related to the maritime strength of the Imperial German Navy.
First World War as it was sent from Washington, DC, to Ambassador
Heinrich von Eckardt, the German ambassador to Mexico. In 1916, during the
First World War, the two sections underwent administrative changes so that the internal counter-espionage section became the Directorate of Military Intelligence Section 5 (
MI5) and the foreign section became the Directorate of Military Intelligence Section 6 (
MI6), names by which the Security Service and Secret Intelligence Service are commonly known today. The
Naval Intelligence Division led the Royal Navy's highly successful cryptographic efforts,
Room 40 (later known as NID25). The decryption of the
Zimmermann Telegram was described as the most significant intelligence triumph for Britain during World War I, and one of the earliest occasions on which a piece of signals intelligence influenced world events. The
Imperial War Cabinet was the British Empire's wartime coordinating body.
Interwar In 1919, the Cabinet's Secret Service Committee recommended that a peacetime codebreaking agency should be created. Staff were merged from NID25 and
MI1b into the new organisation, which was given the cover-name the "
Government Code and Cypher School" (GC&CS). The
Joint Intelligence Committee (JIC) was founded in 1936 as a sub-committee of the Committee of Imperial Defence.
Second World War Following the outbreak of the
Second World War in 1939, the JIC became the senior intelligence assessment body for the United Kingdom government. During the War, the
RAF Intelligence Branch was established, although personnel had been employed in intelligence duties in the RAF since its formation in 1918. The
Special Operations Executive (SOE) was operational from 1940 until early 1946. SOE conducted
espionage,
sabotage and
reconnaissance in
occupied Europe and later in
occupied Southeast Asia against the
Axis powers and aided local
resistance movements. intercept sheet of an
Enigma machine message, after decryption. The 1943 British–US Communication Intelligence Agreement,
BRUSA, connected the signal intercept networks of the GC&CS and counterparts in the U.S. The GC&CS was based largely at
Bletchley Park. Its staff, including
Alan Turing, worked on
cryptanalysis of the Enigma (codenamed
Ultra) and
Lorenz cipher, and also a large number of other enemy systems.
Winston Churchill was reported to have told
King George VI, when presenting to him
Stewart Menzies (head of the
Secret Intelligence Service and the person who controlled distribution of Ultra decrypts to the government): "It is thanks to the secret weapon of General Menzies, put into use on all the fronts, that we won the war!"
F. W. Winterbotham quoted the western Supreme Allied Commander,
Dwight D. Eisenhower, at war's end describing Ultra as having been "decisive" to Allied victory.
Sir Harry Hinsley, Bletchley Park veteran and official historian of British Intelligence in World War II, made a similar assessment about Ultra, saying that it shortened the war "by not less than two years and probably by four years"; and that, in the absence of Ultra, it is uncertain how the war would have ended.
Cold War . The Government Code and Cypher School was renamed the "
Government Communications Headquarters" (GCHQ) in 1946. The Joint Intelligence Bureau (JIB) was established the same year. It was structured into a series of divisions: procurement (JIB 1), geographic (JIB 2 and JIB 3), defences, ports and beaches (JIB 4), airfields (JIB 5), key points (JIB 6), oil (JIB 7) and telecommunications (JIB 8). A British military radio operator working at the
British Embassy in Moscow discovered in 1951 a listening device,
The Thing, at the residence of the
US ambassador to the Soviet Union,
Spaso House when he happened to tune into Soviet monitoring. Wartime signals intelligence cooperation between the United Kingdom and the United States continued in the post-war period. The two countries signed the bilateral
UKUSA Agreement in 1948. Later broadened to include Canada, Australia and New Zealand, known as the
Five Eyes, as well as cooperation with several "third-party" nations, this became the cornerstone of Western intelligence gathering and the "
Special Relationship" between the UK and the USA. Since World War II, the chief of the London station of the U.S.
Central Intelligence Agency has attended the Joint Intelligence Committee's weekly meetings. One former US intelligence officer has described this as the "highlight of the job" for the London CIA chief. Resident intelligence chiefs from
Australia,
Canada, and
New Zealand may attend when certain issues are discussed. The Joint Intelligence Committee moved to the
Cabinet Office in 1957 with its assessments staff who prepared intelligence assessments for the committee to consider. During the
Cuban Missile Crisis,
GCHQ Scarborough intercepted radio communications from Soviet ships reporting their positions and used that to establish where they were heading. A copy of the report was sent directly to the White House Situation Room, providing initial indications of Soviet intentions with regard to the US naval blockade of Cuba. The DIS focussed initially on Cold War issues. As well as a mission to gather intelligence, GCHQ has for a long time had a corresponding mission to assist in the protection of the British government's communications. Building on the work of
James H. Ellis in the late 1960s,
Clifford Cocks invented a
public-key cryptography algorithm in 1973 (equivalent to what would become, in 1978, the
RSA algorithm), which was shared with the National Security Agency in the United States. The
Security Service Act 1989 established the legal basis of the Security Service (MI5) for the first time under the
government led by Margaret Thatcher. GCHQ and the Secret Intelligence Service (MI6) were placed on a statutory footing by the
Intelligence Services Act 1994 under the
government led by John Major.
21st century The
National Infrastructure Security Coordination Centre (NISCC) and the
National Security Advice Centre (NSAC) were formed in 1999. NISCC's role was to provide advice to companies operating
critical national infrastructure, and NSAC was a unit within MI5 that provided security advice to other parts of the UK government. The
Centre for the Protection of National Infrastructure (CPNI) was formed as a child agency of MI5 in 2007, merging the NISCC and NSAC. CPNI provided integrated security advice (combining information, personnel, and physical) to the businesses and organisations which made up the critical national infrastructure. In 2016, the cybersecurity-related aspects of the CPNI's role were taken over by the newly-formed
National Cyber Security Centre (NCSC), a child agency of GCHQ. The CPNI evolved into the
National Protective Security Authority (NPSA) in 2023, taking on a remit beyond critical national infrastructure. The
Office for Security and Counter-Terrorism (OCST) was created in 2007 and is responsible for leading work on
counter-terrorism working closely with the
police and security services. The OSCT was renamed the Homeland Security Group in 2021. The Defence Intelligence Staff changed its name to
Defence Intelligence (DI) in 2009. The
Joint Intelligence Organisation was formalised to provide intelligence assessment and advice on development of the UK intelligence community's analytical capability for the Joint Intelligence Committee and NSC. The heads of the Five Eyes domestic security agencies gave a public presentation together for the first time in 2023. The
MI6 chief and the
CIA director made their first-ever joint remarks in an
opinion piece in the
Financial Times in 2024. ==Budget==