October 2015 release of historical MI5 files
MI5 has released a further batch of 103 historical files. These are now available to view alongside Cabinet Office and Foreign and Commonwealth Office files at The National Archives, and bring the total number of MI5 files held there to 5,449.
Most of the newly released files concern Cold War investigations in the 1950s, notably those focused on the Cambridge Five spy ring.
Included are details of MI5’s search for Soviet agent HOMER which, following a project VENONA breakthrough, identified Foreign Office diplomat Donald Maclean. Maclean had been passing information on the British negotiating position for talks between Churchill, Roosevelt and Stalin.
The files also reveal how surveillance of Maclean spotted him meeting Guy Burgess shortly before the pair fled to Russia. They show that Burgess previously worked with agents on behalf of MI5 during World War II, and note some of his vices.
For more information, see The National Archives press release.