Britain's spy agency officially did not exist until 1994
MI6 was founded in 1909 and spied through two world wars, yet the British government only admitted it existed in 1994, when a new law finally gave it a legal basis. Even its famous nickname was a wartime convenience; its proper title is the Secret Intelligence Service, run by a chief known simply as C.
The service began as the foreign section of the Secret Service Bureau in 1909, expanded sharply during the First World War and took the name Secret Intelligence Service around 1920. During the Second World War it went by many labels, and MI6, short for Military Intelligence, Section 6, was simply the handiest one. It stuck. The Intelligence Services Act 1994 gave the service a basis in law, and that same year it moved into its headquarters on the South Bank of the Thames in London.
Its job is gathering human intelligence abroad. Unlike MI5, which handles domestic security, and GCHQ, which specialises in signals, SIS may by law only operate against people outside the British Islands, though it works closely with both and shares material with the Five Eyes partners. Its declared priorities are counter-terrorism, halting the spread of weapons, supporting cyber security and promoting stability overseas.
Accountability runs through the Foreign Secretary, who appoints the chief and receives reports directly, while the Prime Minister carries overall responsibility for security. The chief has two faces: managing agents, risk and technology inside the service, and acting as a covert diplomat who maintains alliances and opens quiet channels to countries where formal relations are strained. Blaise Metreweli took the post in 2025. The Joint Intelligence Committee weighs material from all three agencies and briefs ministers, and the Investigatory Powers Tribunal and Parliament's Intelligence and Security Committee provide outside oversight.
Money is handled discreetly too. The agencies prepare annual accounts under a 2000 law, but the government keeps them unpublished; the Comptroller and Auditor General audits them and shows them only to the chair of the Public Accounts Committee. Figures for 2021 to 2022 put combined spending across British intelligence at £3.44 billion. Controversy has not been avoided: since the 2000s the service has faced allegations of complicity in torture and extraordinary rendition.
Source: MI6
