John Alexander Sinclair

Sir John Alexander Sinclair, (29 May 1897 – 22 March 1977) was Head of the Secret Intelligence Service from 1953 to 1956.

Career
Sinclair was commissioned into the Royal Army Service Corps. In 1938 he was appointed an Instructor at the Staff College, Camberley. By 1941 he was Deputy Director of Operations at the War Office and then in 1942 he became Director Royal Artillery for 1st Division. In 1944 he was appointed Director of Military Intelligence at the War Office. In 1946, while still in the British Army he started working for the Secret Intelligence Service.

Following his retirement from the military in 1952, as a Major-General, he was appointed head of the British Secret Intelligence Service, taking up the post in 1953. He led the Service through the translation from its wartime operations, directing operations in the emerging Cold War environment in a "practical and responsible fashion", "instead of accommodating the risk takers". He also introduced reforms to recruitment and conditions of service designed to introduce a professional career structure within SIS suited to post-war conditions. His personal integrity was recognised not just by colleagues, but also by opponents.

Sir John's retirement coincided with a failed frogman mission to investigate the Soviet cruiser Ordzhonikidze that had brought the leader of the Soviet Union Nikita Khrushchev and Prime Minister Nikolai Bulganin on a diplomatic mission to Britain, resulting in the death of frogman Lionel Crabb. The Prime Minister had not approved this mission and some accounts incorrectly claimed that Sir John had been forced to resign. The Authorized History of MI5 confirms however that the decision that the head of that service should succeed Sir John at his planned retirement date in 1956 had been taken by the Prime Minister in 1954.