David Cameron moved to stamp his mark on the Tory party after emerging as the clear winner in its leadership contest today, using his victory speech to promise a "modern, compassionate Conservative Party" that had the courage to change the way it looked, thought and acted.

The 39-year-old MP for Witney, considered a distant outsider for the leadership only two months ago, capped his meteoric rise through the party ranks by beating David Davis by 134,446 votes to 64,398 in a ballot of party members - a winning margin of more than two to one.

He becomes the party's fifth leader in eight years, replacing Michael Howard, who announced that he was standing down after Labour won its third straight election in May but managed to stay around long enough to see the party leadership skip a generation.

Mr Davis, the pugnacious standard-bearer of the Right, was gracious in defeat, saying that the contest had not just been for the leadership of the Conservative Party but the "preamble" to a Tory victory at the next election.

And Mr Cameron himself immediately showed the oratorical skills which sent his star soaring at the party conference in Blackpool when he took to the stage at the Royal Academy to tell senior party members that the next election was theirs for the winning.

His main message was that the party must change, not just the way it looks, by selecting more female MPs, but also the way that it thinks and acts. "I am fed up with the Punch and Judy politics of Westminster," Mr Cameron said.

And he signalled a party that would be more focused on social and economic justice, picking up on a much-quoted line from Margaret Thatcher that "there is no such thing as society".

"There is such a thing as society, it's just not the same thing as the state," Mr Cameron said.

Elected to Parliament in 2001, Mr Cameron was widely seen as being too inexperienced to challenge for the top job when the May election defeat set the ball rolling on the party's longest ever leadership contest.

But a supremely confident performance at the party conference in October, when he persuaded delegates that he was a potential election-winner, saw Mr Cameron displace Mr Davis as frontrunner. After the elimination of Kenneth Clarke and Liam Fox in two rounds of voting by MPs, Mr Cameron and Mr Davis were the final two candidates put foward to members.

In his victory speech, Mr Cameron said he expected Mr Davis to play an active role in his leadership team. But asked afterwards whether he would offer Mr Davis a senior Cabinet post, he said people would have to "wait and see".

He added: "You are going to see a very strong shadow cabinet that brings in all the great talents of our party. And David is one of the great talents of our party."

He was later asked why his "euphoric launch" should be any different to his predecessors’ - who had all been defeated.

"This is my first one," he replied. "There is in the Conservative Party today a great sense of unity and coming together. People in the Conservative Party, people in this country are fed up with a government that they feel is getting so much wrong.

"They want that modern compassionate Conservative alternative that I am offering. I think we can go forward as a very united party with a real sense of purpose about what is wrong in this country, about why Labour can’t put it right, and about why, if we have the courage to change, we can."

Mr Cameron also attacked Gordon Brown - the man he is likely to face at the next election. He said the Chancellor "cannot escape from his past" of increasing tax and regulation and holding back reform. "He is the great road-block," he said. "He is the person who is holding Britain back. And in order to get that road-block out of the way we need a Conservative government."

Mr Cameron is the first Old Etonian to head the Tories since Sir Alec Douglas-Home more than 40 years ago. He is generally seen as being on the Left of the party, a leader of its modernising Notting Hill set, although he is also a strong Eurosceptic.

The first test of his leadership skills will come in tomorrow's Prime Minister's Questions, when he faces up to Tony Blair for the first time. On Thursday he is due to name his shadow Cabinet, with William Hague, the popular former party leader, expected to be given one of the main portfolios.

Although Mr Howard was much criticised after the election for not stepping aside immediately to ensure a seamless transition, he said today that the events of the past seven months had helped to create a new mood in the party and the country. If his successor was able to exploit that new mood, he said, "then absolutely everything is possible".

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