The newly-declassified documents include details about some of the UK'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.

Rookie wartime MI5 "watchers" were advised they needed to be prepared to offer a big tip if they had to tell a taxi driver to "follow that cab" when pursuing a suspect, newly declassified documents reveal.

Despite advances in electronic surveillance, security service MI5 still relies on human ‘watchers’. Government documents reveal what it takes to follow suspects without being detected.

MI5 reveals confessions of three members of infamous Cambridge Five spy ring as tranche of documents released into National Archives

Recently released MI5 files reveal confessions from Britain's notorious double agents, including Kim Philby and Anthony Blunt, who spied for the Soviets. These declassified documents, made public by the National Archives,

MI5 feared film star Dirk Bogarde could be the target of a KGB gay "entrapment" attempt after it emerged he was on a list of 'six practising British homosexuals' passed to the Russians

The guidance is contained in a booklet for recruits during World War Two, which will go on display at the National Archives in Kew, west London Rookie wartime MI5 "watchers" were advised they ...

The MI5 files, released to the National Archives, reportedly contain Blunt’s full confession. Shortly before he was set to retire at age 65, Blunt came clean in April 1964 to MI5 interrogator ...

The guidance will feature in a new exhibition at the National Archives focusing on the work of the Security Service.