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.

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.

The manual gives instructions on preferred appearances, disguises and how to follow targets – but warns against fake moustaches

Avoid false beards, carry plenty of spare change and know what to do when you need to tell a taxi driver "follow that cab!" - these were some of the tips given to rookie MI5 "watchers".

Anthony Blunt, who worked at Buckingham Palace as Surveyor of the Queen’s Pictures, was secretly a Soviet spy during WWII.

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.