Was Cairncross, then, a spy too? As he sweated in the interrogation ... In April that year he wrote to John Winnifrith, the Treasury boss who, two weeks earlier, had suspended him pending ...

“The release reveals new details in the cases of the Cambridge spies Kim Philby, Anthony Blunt and John Cairncross ... loyalty” to Britain’s MI6 spy agency, where he served as a high ...

Several other people have been suggested as belonging to the ring, including John Cairncross ... the British government discovered he was a spy but offered him immunity in return for information.

Blunt and 'fifth man' Cairncross became synonymous with treachery at the heart of the British establishment. A KGB agent names the Cambridge spy ring's 'fifth man'.