The 2010 United Kingdom general election was held on Thursday, 6 May 2010, with 45,597,461 registered voters entitled to vote to elect members to the House of Commons. The election took place in 650 constituencies across the United Kingdom under the first-past-the-post system. None of the parties achieved the 326 seats needed for an overall majority. The Conservative Party, led by David Cameron, won the largest number of votes and seats, but still fell 20 seats short. This resulted in a hung parliament where no party was able to command a majority in the House of Commons. This was only the second general election since the Second World War to return a hung parliament, the first being the February 1974 election. Unlike in 1974, the potential for a hung parliament had this time been widely considered and predicted, and both the country and politicians were better prepared for the constitutional process that would follow such a result. The coalition government that was subsequently formed was the first coalition in British history to eventuate directly from an election outcome. The hung parliament came about in spite of the Conservatives managing both a higher vote total and higher share of the vote than the previous Labour government had done in 2005, when it secured a comfortable majority.
Coalition talks began immediately between the Conservatives and the Liberal Democrats, and lasted for five days. There was an aborted attempt to put together a Labour/Liberal Democrat coalition (although other smaller parties would have been required to make up the ten seats they lacked for a majority). To facilitate this, Gordon Brown announced on the evening of Monday 10 May that he would resign as Leader of the Labour Party. Realising that a deal with the Conservatives was within reach, the next day on Tuesday 11 May, Brown announced his resignation as Prime Minister, marking the end of 13 years of Labour government. This was accepted by Queen Elizabeth II, who then invited David Cameron to form a government in her name and become Prime Minister. Just after midnight on 12 May, the Liberal Democrats emerged from a meeting of their Parliamentary party and Federal Executive to announce that the coalition deal had been "approved overwhelmingly", sealing a coalition government of Conservatives and Liberal Democrats.
None of the three main party leaders had previously led a general election campaign, a situation which had not occurred since the 1979 election. During the campaign, the three main party leaders engaged in a series of televised debates, the first such debates in a UK general election campaign. The Liberal Democrats achieved a breakthrough in opinion polls after the first debate, in which their leader Nick Clegg was widely seen as the strongest performer. Nonetheless, on polling day their share of the vote increased by only 1% over the previous general election, and they suffered a net loss of five seats. This was still the Liberal Democrats' largest popular vote since the party's creation in 1988, and they found themselves in a pivotal role in the formation of the new government. The share of votes for parties other than Labour or the Conservatives was 35%, the largest since the 1918 general election. In terms of votes it was the most "three-cornered" election since 1923, and in terms of seats since 1929. The Green Party of England and Wales won its first ever seat in the House of Commons, and the Alliance Party of Northern Ireland also gained its first elected member. The general election saw a 5.1% national swing from Labour to the Conservatives, the third-largest since 1945. The result in one constituency, Oldham East and Saddleworth, was subsequently declared void on petition because of illegal practices during the campaign, the first such instance since 1910.
The Prime Minister, Gordon Brown, went to Buckingham Palace on 6 April and asked the Queen to dissolve Parliament on 12 April, confirming in a live press conference in Downing Street, as had long been speculated, that the election would be held on 6 May, five years since the previous election on 5 May 2005. The election took place on 6 May in 649 constituencies across the United Kingdom, under the first-past-the-post system, for seats in the House of Commons. Voting in the Thirsk and Malton constituency was postponed for three weeks because of the death of a candidate.