Opinion polling for the 2010 United Kingdom general election

Cameron duly did so, forming a government in coalition with the Liberal Democrats, and making Clegg deputy prime minister.

Therefore, the first past the post system means that the number of MPs elected may not reflect the overall popular vote share across the parties.

[4] That said, in previous elections, approximate forecasting of results were achieved by assuming that the swing in each individual constituency will be the same across the country.

[5] By using UNS projections, several media commentators and politicians have suggested that significant swings towards the Liberal Democrats in the opinion polls may not necessarily amount to significant gains in terms of parliamentary seats, including predictions that even if the Liberal Democrats had the most votes, and Labour the least, it could be the case that Labour retains the most seats while the Lib Dems have the fewest.

Below that level there is a danger of by-elections and MPs crossing the floor of the House of Commons reducing the government to a minority such that it would be at increased risk of losing a vote of no confidence.

Immediately following the previous general election, the Labour Party held a double-digit lead in opinion polls.

From the May 2006 local elections, in which Labour suffered significant losses, the Conservatives took a small single-digit lead in opinion polls.

Labour regained the lead in June 2007, following the resignation of Tony Blair as prime minister and the selection of Gordon Brown as his successor.

Brown resisted calls from his party to hold a general election, despite opinion polls suggesting that Labour was capable of being re-elected at this stage.

By the end of February 2010, Ipsos MORI, ICM, YouGov and ComRes polls had all found a sufficient narrowing of the Conservative lead for media speculation about a hung parliament to return - scenario which could have allowed Labour to cling onto power in a minority or coalition government.

In some polls, the Liberal Democrats took the lead from the Conservatives by a narrow margin which was unprecedented in the period since the Lib Dems were founded in 1988.

The following graph shows ComRes poll results recorded over the period 11 April – 6 May 2010, including annotations of the three TV debates.