Unite against Brown, Tories urged

In a rallying speech as Mr Brown prepares to enter Number 10, Mr Cameron called on Tories to hold the centre ground and not return to "old tunes" which had left them in the wilderness for a decade.

He moved to placate anger among traditionalists over the long-running grammar schools row, stressing his commitment to a "grammar stream" in each school.

However, Mr Cameron refused to bow to pressure from some on the right who want immediate pledges of tax cuts - insisting only that the burden would be reduced "over time".

Labour immediately branded the address in south London a "Save Dave" speech designed to gloss over disarray in his own ranks.

Setting out his "big idea" of "social responsibility", the Conservative leader promised a more local approach, rather than the "top down" control favoured by Mr Brown.

"Social responsibility means that every time we see a problem, we don't just ask what the government can do," he told an audience of party supporters in south London.

"We ask what individuals can do, what society can do. That's the big difference between us and Gordon Brown. His answer to crime, his answer to education or health, his answer to everything - is a top down government scheme."

He added: "Under Gordon Brown all we get is "he knows best" politics, as he sits at his desk expecting a grateful nation to wait with bated breath while the next great masterplan emerges."

Mr Cameron dismissed criticism that he has been abandoning Conservative principles to copy New Labour, insisting that he was intent on making his party the "true force of progressive politics in Britain today".