The newly-declassified documents include details about some of the UK's most notorious spies.

Queen Elizabeth II was not told about her long-time art adviser's double life as a Soviet spy, newly declassified documents reveal.

Secret UK Files Detailing Confessions of Cambridge Five Spies Released By Michael Holden ... Cairncross, the last of the spy ring to be publicly identified in the 1990s, admitted in a 1964 interview in the U.S. that he too had been recruited by Russian ...

Anthony Blunt, a royal art historial, confessed in 1964 to spying for the Soviets, but the late queen was not officially told about his past until 1973. View on euronews

Top secret MI5 files detailing first-hand accounts of confessions of three of Britain's most notorious double agents including Kim Philby and Anthony Blunt who spied for the Soviet Union were released for the first time on Tuesday.

A World War II-era tailing guide is among declassified records shedding light on spy game in MI5: Official Secrets, at the National Archives.