Today we have released the latest collection of records from MI5 spanning the 1930s to the 1970s.
The files, once classified secret or top secret, shed new light on political surveillance, prominent cultural figures and Soviet espionage in Britain.
Among those featured is Aneurin Bevan, the Labour politician best remembered as the founder of the NHS. The records show that MI5 monitored his pre-war activities and associations with communists, although no action was taken beyond surveillance.
Other files concern the composer Sir Michael Tippett, who joined the Communist Party in 1934 and was imprisoned during the Second World War after failing to comply with the conditions of his registration as a conscientious objector.
The release also contains a brief reference to Dad’s Army actor and playwright Arnold Ridley, who accompanied Sylvia Matthews when she gave police a statement about a passport obtained for a German communist.
One of the largest groups of files traces the investigation of Frank Clifton Bossard, a former RAF officer who sold British missile secrets to Soviet intelligence. MI5 placed Bossard under close surveillance, bugged his home and followed him as he photographed classified documents in London hotels. He was arrested in March 1965 and later sentenced to 21 years in prison.
Further records cover Operation FOOT, the expulsion of 105 Soviet officials linked to espionage in September 1971.
The newly released files will be available to view and download through Discovery, our catalogue, from today.
Read more about the release in our blog.