LONDON (AFP) - Britain is voting in the closest general election for decades, with polls suggesting David Camerons opposition Conservatives will win most seats but not enough to form a majority government. Beleaguered Prime Minister Gordon Brown faced a long election night wait to learn his fate, after polling booths close at 10:00 pm (2100 GMT) in the knife-edge ballot. The Liberal Democrats, Britains traditional third party, could emerge as kingmakers in a power-sharing deal after making a spectacular surge during a gruelling month-long campaign. Election day was marked by a protest outside the polling station where Cameron voted, and a plane crash which injured a high-profile anti-Europe candidate. Cameron, battling to end the Conservatives 13 years in opposition, was the first of the main party leaders to vote after urging supporters to give this country the hope, the optimism and the change we need. Several eve-of-election polls showed the Conservatives had a clear lead over Browns ruling Labour Party and Nick Cleggs Liberal Democrats. But they suggested that under Britains first-past-the-post system, Camerons Tories would fall short of an overall majority in the House of Commons, setting up the first hung parliament since 1974. A poll by ICM for the Guardian newspaper predicted Conservative support had increased slightly to around 36 percent, with Labour unchanged on 28 percent, while the Lib Dems had fallen back to 26 percent. That would roughly equate to 283 seats for the Tories, 253 for Labour and 81 for the Lib Dems. Such an outcome would spark a scramble for power, with Cameron seeking a partner to govern, or forcing through a minority government, possibly with the support of a handful of lawmakers from Northern Ireland. More than 44 million voters were called to the polls, with observers predicting turnout could be as high as 70 percent after an unusual campaign transformed by the first televised leaders debates in a British election. A smiling Cameron and his wife Samantha voted in the picturesque village of Spelsbury in his Witney constituency in Oxfordshire, north of London. Earlier, two pranksters climbed on to the roof of the polling station and unfurled a banner drawing attention to Camerons education at the elite fee-paying Eton College, which has produced 18 British prime ministers. Britons know your place. Vote Eton vote Tory, read the banner, held by two young men, one dressed in a blazer and a straw boater hat, who were later persuaded to climb down by police and taken away for questioning. Brown, who has been fighting for his political life in a frantic week of campaigning, was accompanied by his wife Sarah as he voted in steady drizzle in Fife in Scotland. Clegg, whose partys surprisingly strong showing has made the election so close, cast his ballot in Sheffield, northern England. Nigel Farage, a high-profile candidate for the eurosceptic UK Independence Party (UKIP), suffered minor head injuries and needed heart tests after the light aircraft he was travelling in crashed at an airfield in Northamptonshire. His campaign manager said the pilot desperately tried to call for help in the seconds before impact. Apparently the plane nose-dived. We had a banner attached to the back of the plane which basically got wrapped around the tail, said Chris Adams. Its all a bit of a shock, especially on polling day. Brown, who took over from Tony Blair as prime minister in 2007, ended his campaigning in his native Scotland and issued a last-ditch plea to wavering voters to back Labour as the best party to safeguard the countrys fragile recovery from a deep recession. At this moment of risk to our economy, at this moment of decision for our country, I ask you to come home to Labour, he urged a crowd in Dumfries. Clegg pleaded with voters to back him and seize a once in a generation opportunity to do things differently. The Lib Dems transformed the election into a three-horse race after his assured performance in the TV debates introduced him to a wider public. For a while, a surge of support propelled the party out of their traditional third position into second position ahead of Labour in many polls, but their poll rating faded towards the end of the race.