What are the precedents for a vote?

Iain Duncan Smith was the last Tory leader to be ousted in a vote of no confidence when he was forced to resign in 2003, although the party was not in power at the time.

The former leader was unpopular among his MPS due to his perceived inability to connect with voters and therefore be elected prime minister.

Sir Michael Spicer, chairman of the 1922 Committee, announced he had received at least 25 votes, the threshold at the time and a vote of no confidence was held on 29 October. Mr Duncan Smith lost the vote 75–90.

The last time a sitting prime minister lost a vote of no confidence was in 1979 when Labour’s James Callaghan lost by one vote. This was a different kind of motion because it was a Commons vote on the government rather than just a party vote on its leader.

Labour, which was presiding over a hung Parliament at the time, was behind in the polls when a motion of no confidence was called by then leader of the opposition, Margaret Thatcher.

After the government lost the vote, Mr Callaghan was forced to call an election, which Labour subsequently lost. Before 1979, the last successful motion of no confidence occurred in 1924.

A vote of no confidence means the UK government has 14 days in which to win a vote of confidence or a general election must be held.