Voice of 'Cambridge spy' Guy Burgess revealed
17 January 2014 Last updated at 21:27 GMT
An audio recording featuring the voice of Guy Burgess, the "Cambridge spy", has been broadcast for the first time.
The recording, obtained by Channel 4 News, features Burgess recounting a day in 1938 when he visited the Kent home of Winston Churchill - long before Churchill became Prime Minister.
The audio tape was released by the US government to City University London researchers Professor Stewart Purvis and Jeff Hulbert, and was recorded by Guy Burgess in New York in 1951.
This audio clip features the recording, put into context by Professor Stewart Purvis.
Audio courtesy Channel 4 News