28 March 1979 was one of the most dramatic nights in Westminster history.
James Callaghan's Labour government lost a confidence motion by one vote and was forced to call an early General Election that would sweep Margaret Thatcher to power.
BBC Parliament is marking the 30th anniversary of that night with a special evening of programmes, The Night the Government Fell.
A Parliamentary Coup tells the story of what happened that night, with testimony from former Downing Street insiders, ministers and party managers about the increasingly frantic attempts to secure the vote for Labour.
In five years as a minority Government, Labour had struck deals with various smaller parties in order to survive but, by March 1979, after a winter of industrial strife, their luck was running out.
Even on the day of the vote, it looked too close to call.
It was only as the night wore on that it became clear that two key abstentions - and the absence of a gravely ill MP - would cost them the vote.