Five Cambridge University graduates served as double agents, leaking highly classified information to 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.

Confessions of double agents and tips for new spies have been released as part of a tranche of recently-declassified documents from MI5. The documents are part of a new exhibition on display at the National Archives this spring and include details about some of Britain's most notorious spies.

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