The Tories have so far gained more than 200 seats in what members have hailed as a 'vote of positive confidence' for their party. Labour have lost 300.

"I think these results are not just a vote against Gordon Brown and his Government. I think they are a vote of positive confidence in the Conservative Party," David Cameron said.

"I think this is a very big moment for the Conservative Party, but I don't want anyone to think that we would deserve to win an election just on the back of a failing Government."

Children's Secretary Ed Balls, a close ally of the Prime Minister, said Labour's losses could not be dismissed as a "mid-term, normal set of problems".

But he insisted he did not sense any "big switches" to the Conservatives.

"I think this is about Labour supporters. They are cross, they are angry and we need to do a lot more to show that we are on their side."

Labour has lost control of six local authorities across England and Wales and gained just one from no overall control, while the Tories have gained more than 12 authorites from no overall control, and claimed a further one from Labour and one from the Liberal Democrats. The Lib Dems bagged four councils from no overall control, including Sheffield.

The Tories would enjoy a landslide Commons majority if the results were repeated in a General Election.

Even seats in heartland councils in Wales fell from Labour control, with the party losing Valleys strongholds of Caerphilly, Merthyr Tydfil, Blaenau Gwent and Torfaen.

The Conservatives gained victory in the Vale of Glamorgan - a must-win council if David Cameron is on course for a General Election victory.

In Nuneaton, Warwickshire, where a Tory victory ended 34 years of Labour control of the Town Hall, Mr Cameron said no political heartlands are off-limits to the Conservatives.

"I don't believe ever in politics there are heartlands that are unwinnable," he said. "No seat is entirely safe."

In London, one bookmaker this afternoon announced it was paying out on a Boris Johnson victory for the Conservatives, hours ahead of the final result.

By 5.45pm, Mr Johnson was ahead on first-preference votes in eight out of the 14 constituencies, with Mr Livingstone ahead in the remaining six.

In Enfield and Haringey, the vote looked extremely close, leaders having changed place during the afternoon.

Bookmaker Paddy Power said the "mauling" Labour had received elsewhere in England and Wales suggested the Conservative candidate was on his way to City Hall.

Mr Johnson was more cautious. "I think the party's done fantastically nationally but London is a very different kettle of fish," he said. "We'll have to see what happens."

Gordon Brown pledged to "learn the lessons" and admitted it had been a "bad" and "disappointing" night for the party.

"It's clear to me that this has been a disappointing night, indeed a bad night for Labour."

He insisted the party "had listened" and would now "move forward".

Mr Brown said he was "sad" for all the Labour councillors who had lost their seats in the poll rout and blamed "difficult economic circumstances" for much of the bad performance.

The Premier insisted the effect of measures taken by the Government to counter problems would become clear "over the next few months".

"I think people want to be assured, and indeed people are questioning and want to be assured, that the Government will steer them through these difficult times."

He added: "The test of leadership is not what happens in a period of success but what happens in difficult circumstances."