Labour then, like the Tories now, seemed hopelessly adrift. James Callaghan had resigned as leader after being defeated the year before by Margaret Thatcher. Ambitious MPs had a sinking feeling they would be out of power for many years. There seemed little point in working on policies which had almost no chance of being implemented. Roy Jenkins, with other leading figures, was actively planning to set up an alternative, Social Democratic Party.
Michael Foot's speech stays in my memory as one of the most enjoyable occasions I witnessed in the House of Commons. I soon forgot the context and simply remembered one of his jokes. A new book by a young expert on Labour history, Greg Rosen, has now delightfully reminded me of exactly what happened. But instead of peppering his book with opinions and hindsight, he gives us long extracts of what politicians actually said. It is a blessed relief.
The most important "ism" that Labour had to tackle at this stage was "monetarism"; it was only later that "Thatcherism" emerged as a far more potent Tory doctrine. The Labour government had accepted that to combat inflation some attempt should be made to control the money supply. It was the monetarists' insistence that you could accurately measure the money supply, and when this figure rose too rapidly all you had to do was to jack up interest rates, which Labour rightly scorned.
This was where Michael Foot's brilliant speech came into its own. His target was Sir Keith Joseph, the highly intelligent but rather dotty Trade and Industry Secretary, who once jumped into a taxi and shouted at the driver "Where am I going?" Foot claimed that Sir Keith, with his puzzled and forlorn manner, reminded him of a magician he used to see in his youth at a theatre in Plymouth. When he asked for an expensive watch, a plant in the audience would rise to his feet. The magician would relieve him of a marvellous gold watch, and proceed to smash it with a mallet.
"Then on his countenance," Mr Foot explained with relish, "would come exactly the puzzled look of the Secretary of State for Industry. He would step to the front of the stage and say 'I am very sorry. I have forgotten the rest of the trick.' It does not work." As Labour MPs roared with laughter at the obvious reference to the monetarist experiment, Mr Foot continued in mock-serious vein. "Lest any objector should suggest that the act at the Palace Theatre was only a trick, I should assure the House that the magician used to come along at the end and say 'I am sorry, I have still forgotten the trick.'"
What Mr Foot's speech achieved was similar to the effect that David Cameron managed in Blackpool. He gave the battered Labour troops the sense that a breakthrough was possible. Others, including the formidable Denis Healey, might also be able to mount a devastating attack on the government's economic policy but to many Labour MPs he looked like a trimmer. Michael Foot, in their eyes, was "Real Labour".
Mr Foot beat Mr Healey by 139 votes to 129. If only six MPs had voted the other way the most popular politician in the country would have won instead of Mr Foot and the recent history of British politics might have been radically different. Politics is often about the moment: capture the mood and you may capture your party. What then happens, of course, is another matter.
This book covers a wide range of dramatic moments, from the creation of the Labour Representation Committee - the start of the Labour Party - at the end of the 19th century, right through to the run-up to Tony Blair's great victory of 1997. Often the story is dominated by the clash between the party's Left and Right, but many of the arguments now seem weirdly out of date. The outline remains, but the passion has long since faded. Spain and the Civil War gets a chapter on its own, and towards the end Mr Rosen traces the interminable battles over nuclear disarmament.
Tories who think their present difficulties are insurmountable should be cheered by this account. It shows how even near-death experiences at Westminster can eventually be overcome. For those seriously interested in politics, Rosen's book is a must-buy.
John Sergeant is the author of 'Maggie: Her Fatal Legacy' (Pan)