Chris Fisher, political editor12.30am: David Cameron is walking towards 10 Downing Street to take over as Britain's prime minister after the Tories won the lion's share of the vote in the general election.Chris Fisher, political editor

By Chris Fisher, Political editor

David Cameron is walking towards 10 Downing Street to take over as Britain's prime minister after the Tories won the lion's share of the vote in the general election.

He may have fallen some way short of a Commons majority of 326 seats, however, and may yet face a choice between running a minority government and reaching a pact with Liberal Democrat leader Nick Clegg. But he quickly signalled that if has won just over 300 seats, he will consider that enough to govern on his own - notwithstanding the turmoil on the financial markets that will greet the new government.

Labour's 13-year rule is almost definitely over. And later today or tomorrow, Gordon Brown will have to leave Downing Street after leading his party to a crushing defeat - in which it looked to have suffered a big swing against it of about 6pc..

An exit poll published just as the voting ended at 10pm confirmed recent opinion polls in indicating that the nation had voted either to give Mr Cameron a slender overall majority in the Commons or for a hung parliament in which the Tories are the largest party. Either way, it was hard to see any alternative to the Conservative leader becoming the head of the next government.

The exit poll predictions were Tories 307 seats (from about 38pc of the votes), Labour 255 (30pc) and the Lib Dems 55 (23pc). If they accurately reflected the real votes, the Conservatives would be left 19 seats short of a majority, and unable to build one with Ulster Unionists.

But it was possible that the actual election results would show that the Conservatives had secured a bigger swing in the key marginal seats than overall. If so, they might get to the 326 target or very close to it, and certainly be able for a while to govern on their own without a deal with, or concessions to, another party.

The first real result, from Houghton and Sunderland South - a safe Labour seat - showed an 8.4pc swing from Mr Brown's party to the Conservatives. If repeated across Britain, that would give Mr Cameron a Commons majority of over 40. In neighbouring Washington & Sunderland West, there was an even bigger swing to the Tories of 11.6pc. But in Sunderland Central, which had been an outside Tory hope, Labour kept the swing down to 4.8pc and comfortably retained the seat.

There were reports of the elector turnout being significantly up on 2005's 61pc, and of queues of people having the doors of polling stations shut in their faces at 10pm. In one polling station voters were said to have been allowed to make their choices after that deadline.

The exit poll statistics looked to have understated the position of the Lib Dems, who normally do better than crude voting shares suggest. And the poll also excluded postal votes.

It nonetheless looked very much like a political death sentence for Mr Brown. It signalled that Labour would lose close to 100 seats, and that even if he and Mr Clegg were able to reach an agreement, they would not be able to command a Commons majority.

The voting seemed to have left Mr Cameron with the lead role in tackling Britain's fiscal deficit, and bringing about the radical changes to the machinery of government that a disillusioned electorate is believed to want. But over 60pc of the voters had apparently voted for something other than the Tories. It was not exactly a great mandate or vote of confidence, and the pressure for electoral reform is now likely to continue and increase.

If the Tories have only narrowly missed out on an overall majority, Mr Cameron is fully expected to reject the idea of a coalition or full pact with the Lib Dems, and opt for running a minority administration.

He would lose no time in confirming George Osborne as the new chancellor of the exchequer, and he would be charged with presenting an 'emergency' budget to the Commons within 50 days. This would feature �6bn of spending cuts this year, the partial scrapping of Labour's plans for national insurance rises nest year - and possibly an increase in VAT to 20pc or just short of that rate.

If the budget were rejected in the Commons, the country would then face going to the polls again in July, and Mr Cameron would hope to capitalise on public anger over that - and a desire for stability - after accusing Labour and the Lib Dems of putting party before country.

They would throw that accusation back at him, and would charge him with arrogantly acting as if the nation had given him a Commons majority when it hadn't.

Labour's defeat - its worst since 1983 - could be the prelude to an extremely bloody battle to succeed Mr Brown as its leader. He and his closest supporters will be blamed for throwing away the inheritance left by Tony Blair, but one of his main lieutenants, Ed Balls, will be among the favourites to take over - if he has managed to keep his Yorkshire seat. It is also expected that one of the Miliband brothers, David and Ed - and possibly both - will stand against him.

One way or another, the election result, created a strong possibility of another election in no more than a year. The new prime minister will be keen to strengthen his position in the Commons as soon as he can.

In immediate reaction to the exit findings, Labour deputy leader Harriet Harman spoke of the need for electoral reform, and Tory shadow schools secretary Michael Gove said there had been 'comprehensive rejection of Labour' by the voters.

Lib Dem shadow chancellor Vince Cable expressed scepticism about the exit poll findings. And business secretary Lord Mandelson remained hopeful of trying to create a Labour-Lib Dem pact. He had no problem in principle with trying to form strong and stable government by such an arrangement, he said.