Records created or inherited by the Secret Intelligence Service

The first recorded use of 'institutionalised' clandestine activity in English history is the appointment by Henry VIII of spymaster Thomas Cromwell as his 'private secretary'. Cromwell, and his successor as Elizabeth I's private secretary, Francis Walsingham, intercepted and read the mail of foreign diplomats and English subjects to obtain intelligence on events and activities of interest to the Crown. Walsingham is also known to have had a network of home and overseas informants, covering most major European cities as far afield as the Near East.

The Civil List Act 1782 limited the use of secret service money to the two broad areas of defeating conspiracies against the Crown and country at home, and to obtaining secret information abroad to defeat the machinations of enemies of the Crown and country. As the Foreign Office and the Home Office became established at the same time, responsibilities for gathering information at home and abroad were similarly divided between the two Secretaries of State.

The secret funds were limited to £25,000 per year, to be paid either to the Foreign Secretary or the Commissioners of the Admiralty, both of whom were required to produce accounts within three years. Administration of the secret vote in the Foreign Office fell to the Permanent Under-Secretary of State. These sums were used during the revolutionary and Napoleonic wars, but after 1815 the use of the secret vote declined. In 1825 George Canning, Secretary of State for Foreign Affairs, made one of the two Foreign Office Under-secretaries (a post which later became that of Permanent Under Secretary) responsible for the administration of the Secret Vote for which the Foreign Secretary had to account to the Exchequer (via the Audit Office) under the terms of the Civil List Act of 1782.

The effectiveness of intelligence gathering by reading mails had declined by the early years of the nineteenth century, as embassies began to use more secure methods of communications (including couriers and messengers). From this time the Foreign Office relied heavily on the reports of consuls and ambassadors for secret information.

After the Crimean War, real advances in intelligence gathering were made by the War Office which, from 1857, began to appoint military attachés to overseas diplomatic posts, who reported on the strength of foreign powers' armed forces through diplomatic channels. It was within the War Office that further professionalisation of the country's intelligence gathering operations developed, with a Directorate of Military Intelligence (MI5) being established in 1909. This officially became the Security Service in 1931.

The Secret Intelligence Service (SIS), often known as MI6, is part of the Security Service. The SIS collects the UK's foreign intelligence and provides HM Government with a global covert capability to promote and defend the national security and economic well-being of the UK. The Service is derived from the Foreign Section of the Secret Service Bureau, which was founded in 1909.