General Elections in the UK have seen plenty of surprising moments occur within them, but a question that some people might wonder is if a Prime Minister has ever lost their seat.

Understandably, leaders of a party are usually placed in very safe seats with a large majority, meaning it would be an extremely difficult task for a candidate from an opposing party to beat them.

However, there is still always a very rare possibility that a party could win the most seats in Parliament but have their leader lose their seat.

Has a Prime Minister ever lost their seat in a UK election?

According to the Institute for Government website, no incumbent (currently holding office) prime minister has ever lost his or her seat at a general election.

There have been Prime Ministers who have won with relatively small majorities though, such as Boris Johnson in 2019 who won by 7,210 votes in the Uxbridge and South Ruislip seat.

The Institute for Government adds: "Two prime ministers have come close to losing their seats. In December 1905, Arthur Balfour resigned as prime minister in an attempt to force an election, but the leader of the opposition, Henry Campbell-Bannerman, instead formed a government and became PM. Balfour went on to lose his constituency at the election a month later.

"In the 1935 general election, Ramsay MacDonald was defeated, having resigned as head of the national government not long before the campaign started." 

Obviously, there have been plenty of cases where the current Prime Minister has won their seat but their party has lost overall.

This meant they could remain as an MP in Parliament, whilst most likely resigning from the leadership position of their party.

What would happen if a Prime Minister lost their seat but their party won?

There is no precedent for this situation occurring so it is difficult to say what would happen in this scenario.

The Cabinet Manual says that a Prime Minister "will normally be the accepted leader of a political party that commands the majority of the House of Commons", but it does not say that this must be the case.

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The Institute for Government states: "However, prime ministers are expected to be accountable to parliament through Prime Minister’s Questions, delivering statements and appearing in front of the Liaison Committee.

"It would therefore not be sustainable for a prime minister to stay in office without being an MP indefinitely."

The most likely thing that would happen is that the Prime Minister would resign, a Cabinet minister of deputy leader would be made an interim PM and then a leadership contest would take place within the party to appoint a new one.