David Cameron was the first of the main party leaders to cast his vote today amid early signs that turnout in one of the most closely contested elections for decades will be high.
As the final polls showed the Conservatives on the brink of regaining power, the Tory leader smiled at reporters and photographers but made few comments at polling station at Spelsbury Memorial Hall in Witney, Oxfordshire.
"I am feeling good, I will leave it at that," he said.
The final Guardian/ICM poll of the campaign showed the Conservatives with an eight-point lead over Labour, just short of what they need for an overall majority. The survey put the Conservatives on 36%, Labour on 28% and the Liberal Democrats on 26%. If the predictions are correct, it could leave Cameron just short of an overall majority, but close to being able to rule with the help of unionist parties.
Half an hour after Cameron voted, Gordon Brown and his wife, Sarah, turned up at the North Queensferry polling station, to cast their vote in the Kirkcaldy and Cowdenbeath constituency.
Minutes later Nick Clegg, accompanied by his wife, voted at a polling station in Sheffield Hallam.
Polling stations opened at 7am, with the electorate having until 10pm to cast their votes. There were early signs of a high turnout. Tellers at polling stations in the London seat of Chingford and Woodford Green reported the busiest start to a general election polling day they could remember.
One said: "Voters have been streaming in from the moment the polling station opened."
The mayor of London, Boris Johnson, predicted an "enormous" turnout as he cast his vote at a polling station in Islington, north London.
"I think this has been a transformatory election campaign. I think people have been more enthused and more interested than by any one I can remember," he said.
Attention on the polls was dramatically diverted when a light aircraft carrying the former Ukip leader, Nigel Farage, crashed in Northamptonshire when a "vote Ukip" banner got caught in the engine.
Farage, who is standing against the Commons Speaker, John Bercow, in Buckingham, escaped with head injuries. The pilot was airlifted to hospital with serious back injuries.
Britain's newspapers sought to assert their influence on the result with dramatic front pages, which mostly backed the Conservatives. The Rupert Murdoch-owned Sun likened David Cameron to Barack Obama by mocking-up an image of the Tory leader in the red and blue stencil style of Obama's iconic Hope posters.
The Sun's stablemate, the Times, carried a front page editorial claiming the Tories were best placed to tackle Britain's debt. The Daily Mail's front page suggested Britain would descend into Greek-style riots if there was a hung parliament.
But the Labour-supporting Mirror questioned David Cameron's credentials as a would-be prime minister by reminding readers of his upper class background. In its last edition it breached copyright restrictions to use the infamous picture of the Bullingdon Club in 1987, which shows the future Tory leader in top coat and tails.
That theme was taken up by two protesters this morning who scaled the roof of Cameron's polling station in his Witney constituency in Oxfordshire.
One of the men dressed in a blazer and boater, unfurled a banner with the slogan "Britons know your place. Vote Eton — vote Tory."
The two men later came down peacefully. The stunt delayed Cameron's planned appearance at the polling station.
As well as the 650 MPs of the new parliament, voters are also electing councillors in 166 local authorities across England – including London boroughs – and mayors in Hackney, Lewisham, Newham and Watford.