It's the loneliest decision of all, they say, when to go for a general election. Turn the clock back thirty years and it was the big question facing the then Prime Minister Jim Callaghan. With industrial strife gripping the country, a slew of manufacturers on their knees asking Government for help, and a dangerous situation brewing in Rhodesia, it was a testing time for Labour.

The secret government files from 1978 have been transferred to the National Archives in Kew, West London and opened to the public. UK CONFIDENTIAL is granted advance access and the team have been sifting through the files, full of phone transcripts, secret minutes and hand written notes.

Joining Martha Kearney is Roy Hattersley (the then Labour secretary of State for Prices and Consumer Protection), David Owen (the then Foreign Secretary), Tom McNally who was Senior Adviser to Jim Callaghan, Leon Brittan (the then Conservative front-bencher) and Matthew Parris who was working in Margaret Thatcher's Research Unit.

A Whistledown Production for BBC Radio 4, in association with Takeaway Media. Producer: Emily Williams.