Now an invited guest at No 10, some see Mr Cameron as PM-in-waiting
With the Conservatives enjoying a significant lead in the polls, and as Gordon Brown reaches his first anniversary as prime minister, the BBC's specialist editors and correspondents examine the depth and breadth of current Tory policies.
First, political editor Nick Robinson explains how the Conservatives reached this point.
Can you imagine David Cameron as prime minister? Do you know what he would do if he made it to No 10?
"Yes and no," say most people, if the polls are to be believed.
Many can see the Tory leader stepping through that door, but few know what he would do if he got there.
Ever since the Tories' electoral triple whammy - winning in the locals, in London and in Crewe and Nantwich - the party and its leadership have been looked at in a different way.
This despite the fact that, as the past year has shown, an awful lot could happen between now and the next election.
BBC senior editors analyse the Conservatives' policies
The Conservatives still have an electoral mountain to climb.
It is for that reason my colleagues and I were asked to examine what Cameron's Britain might look like.
With the country facing its toughest economic times in years, you might think sorting out the economy would be the Conservative leader's top priority - but you would be wrong.
David Cameron does not want and has not argued for a fundamental shift in economic policy - instead he simply makes a case for a lower rate of growth in public spending and, thus, lower taxes in the long run.
So instead he has focused on social policy, promising that he will do for society what Margaret Thatcher did for the economy in the 1980s.
He is promising, in other words, to cure the new British disease - not the failing economy, but what he has labelled “a broken society”.
The Conservatives have spent the last couple of years assiduously trying to convince the electorate that their reputation as the party of wealth and privilege is unfair and wrong
To those who complain that the Tories have abandoned the ground on which they should be fighting, the Conservative leader replies that there is a link between mending society and a strong economy.
Borrowing the language once used by Tony Blair when he was leader of the opposition, he pledges to cut the cost of failure and thus to save money that can be spent on other priorities.
Mr Blair argued that he could cut unemployment and thus not have to put up taxes.
Mr Cameron argues that he can cut welfare dependency, violent crime, drug and alcohol abuse and family breakdown, thereby releasing money that will eventually allow taxes to be cut.
How does he claim to be able to do this?
The answer, Mr Cameron says, is to put and end to “the era of big, bossy, top-down, lever-pulling government” and replacing it with a “bottom-up” approach that encourages what he calls “social responsibility”.
Some critics say this is little more than salesman's patter for an old-fashioned Tory policy of the government doing less and abandoning the poor.
Mr Cameron insists that what he is “groping towards” is an approach in which the government frees and incentivises individuals, families, voluntary organisations and the private sector to do more for themselves, to innovate and produce results the state has so far failed to deliver - despite having vast sums lavished on it.
The most striking feature is how much the vision for education in England has changed under David Cameron, stealing many of New Labour's clothes
It is now conventional wisdom across all the major parties that charities and private companies know better how to spend public money on, say, helping to get people off welfare and into work than any Whitehall bureaucrat.
What the Tories are arguing is that approach could be spread right across what the government does.
Most radically, they want to allow new schools to be set up to compete with existing council-run schools. Choice, the Conservatives believe, will lead to diversity, innovation and progress.
Even if this approach could produce the benefits claimed for it, there are real risks.
If there is more local innovation, there could be more variation in the standards of services, more so-called “postcode lotteries” and fewer central government guarantees about what you can get for your taxes.
More choice, some will claim, will simply lead to waste. What is more, it could benefit those most able to make informed choices and disadvantage those least able to.
Those who now object to commercial intrusion into the NHS or local council services could see it spread even further.
The [Conservative] party has been able to tap into public unease at change in the health service, particularly in England
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