UPDATE: The highlights of the 2015 General Election so far:
- Ed Miliband announces resignation as Labour leader.
- Nigel Farage loses Thanet South and quits as Ukip leader - but leaves the door open to return
- Nick Clegg quits as leader of the Lib Dems after a disastrous election for the party
- Conservatives pass 323 seats, securing a working majority
- David Cameron returns to Number 10 and pledges to unite the country
- Ed Balls loses in biggest shock of the night for Labour
- Other major casualties include Scottish leader Jim Murphy and shadow Foreign Secretary Douglas Alexander
- Vince Cable and Danny Alexander among the major Liberal Democrat casualties
- SNP celebrates 'electoral tsunami' and wins 56 out of 59 seats in Scotland
- Boris Johnson returns to Parliament as MP for Uxbridge
RESULT: DAVID Cameron is on the verge of celebrating an extraordinary and unexpected general election victory today as election results are set to deliver him a second term as Prime Minister and the first majority Conservative government for nearly 20 years.
He pledged to unite the country , "reclaim the mantle of One Nation" and implement further devolution "as soon as possible" after Scottish nationalists romped to victory by winning 56 of Scotland's 59 seats at the expense of Labour and the Liberal Democrats, who lost a string of high profile figures.
There was speculation that Ed Miliband would be forced to resign as Labour leader after a disastrous result - failing to turn a strong campaign performance into votes.
Although his allies made plans for a "Save Ed" campaign during the election's early stages, some Labour figures doubt he could survive such a dismal result. His resignation would spark a huge debate over Labour's future direction between Miliband allies on the soft left and Blairites, who doubted Mr Miliband's "core vote" strategy would appeal to centre ground voters.
In Scotland, Labour's casualties included Douglas Alexander, the shadow Foreign Secretary and the party's campaign chief; Jim Murphy, the leader of Scottish Labour, and Margaret Curran, the shadow Scottish Secretary.
Labour also lost Kirkcaldy and Cowdenbeath, where Gordon Brown stood down. The Lib Dem losers included Ed Davey, the Energy and Climate Change Secretary, in Kingston and Surbiton, and Jo Swinson, the Business Minister, in Dunbartonshire East.
Speaking after winning his Doncaster North seat, Mr Miliband apologised to Labour supporters. "This has clearly been a very disappointing and difficult night for the Labour party," he said.
"We have not made the gains we wanted in England and Wales, and in Scotland we have seen a surge of nationalism overwhelm our party," he said after being comfortably re-elected with an increased majority in Doncaster North.
"I want to say to all the dedicated and decent colleagues in Scotland who have lost their seats that I am deeply sorry for what has happened.
"And I also want to say that the next government has a huge responsibility. It has a huge responsibility in facing the very difficult task of keeping our country together.
"Whatever party we come from, if we believe in the United Kingdom we should stand up for people in every part of our United Kingdom because I believe that what unites us is much, much more than what divides us."
Mr Cameron, speaking after he won his Witney constituency in Oxfordshire, set out his priorities if he continues as Prime Minister: "My aim remains simple - to govern on the basis of governing for everyone in our United Kingdom," he said.
"I want to bring our country together, our United Kingdom together, not least by implementing as fast as we can the devolution that we rightly promised and came together with other parties to agree both for Wales and for Scotland.
"In short, I want my party, and I hope a government I would like to lead, to reclaim a mantle that we should never have lost - the mantle of One Nation, One United Kingdom. That is how I will govern if I am fortunate enough to form a government in the coming days."
The early results were in line with an exit poll suggesting that the Conservatives would enjoy a decisive 77-seat lead over Labour. The survey of 22,000 voters for the BBC, ITV and Sky News predicted the Tories would win 316 seats in the new parliament (up from 307), with Labour on 239 (down from 258); the SNP winning 58 of Scotland's 59 seats (up from six); the Liberal Democrats with just 10 MPs (down from 57); Plaid Cymru four (up from three); Ukip with two MPs - their first at a general election- and the Greens two (up from one).
Some results pointed to an overall majority for the Conservatives. In Warwickshire North, Labour's number one target, the Tories increased their slender 54 majority to 2,977. In Nuneaton, the first marginal to declare, the Tories boosted their 2,069 majority to 4,882 in a key Labour target.
John Curtice, Professor of Politics at Strathclyde University, who worked on the exit poll, said Nuneaton could point to an overall Tory majority. He said: "We were expected a one-point swing to Labour in Nuneaton. In practice, with a three-point swing… we now have to take seriously the possibility the Tories could get an overall majority."
The results suggested that the polls during the campaign, showing the Tories and Labour neck and neck, were flawed. There was speculation that "shy Tories" did not want to admit to pollsters they were backing the party and of a "late break" to Mr Cameron's party. Tory strategists have long hoped for a repeat of the 1992 campaign, when a late swing to the party enabled John Major to win an unexpected majority after voters turned away from Labour.
If the poll proves accurate, Mr Cameron would be close to the 323-seat winning line. Although 326 MPs are needed for an overall majority in the 650-strong Commons, in practice the figure is 323 because Sinn Fein, which had five MPs in the last Parliament, does not take its seats at Westminster and the Speaker does not vote.
If the Tories win the 316 seats forecast by the exit poll, Mr Cameron would need the support of the Lib Dems or Democratic Unionist Party (DUP) to be sure of an overall majority in Commons votes. The PM might be tempted to seek another coalition rather than rely on Eurosceptic in tight votes. But he would face strong pressure from backbenchers, whose leaders meet this afternoon, to run a minority government without a second coalition.
The results painted a picture of "a Disunited Kingdom", with Scotland dominated by the SNP and England by the Tories. It could also leave the governing party at Westminster without any representatives in Scotland, fuelling demands for a "new constitutional settlement" with more powers devolved to Scotland - and possibly another referendum on independence. Labour's inquest will focus on a humiliating defeat in its Scottish powerbase, where voters rejected Labour's "vote SNP, get Cameron" warnings.
A Labour source said: "The results in Scotland are clearly very difficult - if the exit poll is right… The next government will have a huge task uniting country."
But Nicola Sturgeon refused to take the blame. She said that if the Tories remained in power, it would be "because Labour failed to beat the Conservatives in England", adding: " SNP MPs will go to Westminster to stand up for Scotland… against a Tory government."
For months, Tory strategists had been hoping for a "crossover point" in which their party would open a clear lead, and were disappointed that it failed to materialise. Michael Gove, the Conservative Chief Whip, told the BBC: "If the exit poll is right, then David Cameron has won a very handsome victory. He will have secured both an advance on seats and outperformed the expectation of almost every commentator."
Such a result, if confirmed today, would be nothing short of a disaster for Labour. The party hoped to be close behind the Tories in the number of seats, which might have allowed Ed Miliband to build an anti-Tory alliance with the SNP, Plaid Cymru ,the Greens and, possibly, the Liberal Democrats.
Lord Mandelson, the former Cabinet minister, told ITV "it would be very difficult" for Mr Miliband to remain leader if the exit poll proved accurate.
David Blunkett, Labour's former Home Secretary, said: "It's a very bad night for us. We are being swept by the tsunami north of the border." Asked if Mr Miliband should resign, Mr Blunkett replied: "I think we should take our time, we should lick our wounds if we have to and we should think seriously."
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