Categories: British people stubs | British spies | Cold War spies Sir Percy Sillitoe was Director General of MI5, the United Kingdoms internal security service, from 1946 to 1953. ... Current MI5 headquarters in Thames House, London MI5, officially called the Security Service, is a British counter-intelligence and security agency. ... 1953 (MCMLIII) is a common year starting on Thursday. ... 1956 (MCMLVI) was a leap year starting on Sunday of the Gregorian calendar. ... Sir Roger Hollis (1905 - 1973) journalist, and head of MI5. ... Sir John Alexander Sinclair (1897-1977) was a British spy and the head of the U.K. Secret Intelligence Service from 1953 to 1956. ... The Secret Intelligence Service (SIS), more commonly known as MI6 (originally Military Intelligence [section] 6), or Her Majestys Secret Service or just the Secret Service, is the British external security agency. ... 1956 (MCMLVI) was a leap year starting on Sunday of the Gregorian calendar. ... 1968 (MCMLXVIII) was a leap year starting on Monday (the link is to a full 1968 calendar). ... Sir John Ogilvy Rennie (13 January 1914 - 30 September 1981), was the 6th C ie Director of the Secret Intelligence Service (MI6) from 1968-1973. ...