Gale--Declassified Documents Online: Twentieth-Century British Intelligence
Declassified Documents Online: Twentieth-Century British Intelligence, An Intelligence Empire brings together files from five UK government departments to provide researchers with access to detailed, previously classified information on the intelligence services of Britain and her Empire throughout the twentieth century.
- The Security Service (MI5)
- The Ministry of Defence: Communications and Intelligence Records
- The Special Operations Executive
- The Colonial Office: Intelligence and Security Departments: Registered Files (ISD Series)
- The Cabinet Office