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

Britain’s National Archives on Tuesdayreleased declassified MI5 domestic counterintelligence agency files containing the confessions of notorious double agents known as the “Cambridge Five” who spied for the Soviet Union.

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.

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

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