Prime Minister Blair squared up to the new kid on the block yesterday. But the prime minister, who has already seen off four Conservative leaders, found that his latest opponent seemed more interested in taking on his own side.

David Cameron, who was elected on Tuesday by a large majority in a postal ballot of some 200,000 party members, apparently prefers shadow-boxing with a past Tory prime minister to taking on the present Labor one. The new Conservative leader used his victory speech on Tuesday to distance himself, not from Mr. Blair, but from Margaret Thatcher.

One of the Iron Lady’s most famous remarks was: “There’s no such thing as society.” Here is Mr. Cameron: “There is such a thing as society; it’s just not the same thing as the state.” It’s not a bad sound bite, but I wish he hadn’t said it. Mrs. Thatcher was prime minister for nearly 11 years, during which she changed Britain and the world for the better. A man whose only real achievement so far is to have been handed the keys to an almost bankrupt party is foolish to snub the greatest British leader since Churchill. And it was no way to treat a lady who has just celebrated her 80th birthday. Noble birth alone does not make a gentleman.

Mr. Cameron also promised to abandon the confrontational style of politics, and found himself put to the test immediately when he faced Mr. Blair at prime minister’s question time, in which government and opposition leaders engage one another like two parliamentary gladiators.

Spectators doubtless hoped for a thrilling contest. But with Mr. Cameron announcing a new era of consensus, Mr. Blair could rely on his experience to see off the young pretender. It was not so much David and Goliath as Batman and Robin, with the Boy Wonder put firmly in his place.

Mr. Cameron told the prime minister that he would support him on two contentious issues, school reform and climate change. Remembering that he is after all meant to be Leader of the Opposition, Mr. Cameron tried to goad Mr. Blair with another well-rehearsed sound bite: “You were the future once.”

The prime minister knew how to deal with that. He kept coming back to the policy issues, on which Mr. Cameron is clearly still feeling his way. And on the question of global warming, I sense that Mr. Cameron intends to attack Mr. Blair from the Left. The prime minister has been converted to the Bush administration’s approach, favoring new, energy efficient technologies rather than the ruinous emissions targets of the Kyoto treaty. He would like to build new nuclear power stations in the teeth of the Labor Party’s opposition. But Mr. Cameron yesterday indicated that he still believes passionately in Kyoto. Does this mean that he will side with the global environmental lobby against America?

On education, Mr. Cameron is hampered by an immovable fact of life: snobbery. There is a certain kind of Englishman for whom the most important thing about anybody in public life is not what he has done, nor what he stands for, but where he went to school. The best Tory leader must be the one who went to the best school, which is assumed to mean one of the exclusive private schools that cunningly call themselves public schools. Such Englishmen have traditionally been overrepresented in the Conservative Party. If David Cameron were to succeed Tony Blair, he would be the 19th Old Etonian to become prime minister.

There is nothing wrong with Eton: the most famous school in the world, it may even be the best. But families whose children have no escape from mediocre schools do not like to be lectured by Etonians. Mr. Cameron’s upper-class background is as much of an obstacle to getting elected in modern Britain as, say, Senator Kerry’s was for him.

Mr. Cameron is pursuing a strategy of dividing Mr. Blair from his party. Early next year, Mr. Blair will have a showdown with the Labor rebels who defeated him on anti-terror legislation when he tries to pilot through Parliament a bold education bill, introducing ideas based on American charter school experience.

Yesterday, Mr. Cameron indicated that he will support this bill, which opens up the possibility that Mr. Blair might have to rely on the Tories to defeat his own left wing. That would be the beginning of the end for Mr. Blair, for it would invite comparisons with the first Labor prime minister, Ramsay MacDonald, who in 1931 split his party by forming a coalition government with the Conservatives.

The most encouraging aspect of Mr. Cameron’s debut has been his promise not to “play politics” with terrorism. His pronouncements on foreign affairs have hitherto been few, but he gives every sign of following Mr. Blair’s neoconservative policies. It was significant that yesterday he appointed as his foreign affairs spokesman one of the staunchest pro-Americans in British politics: William Hague. Though Mr. Hague was an unsuccessful Tory leader from 1997 to 2001, he is a brilliant speaker, wrote a fine life of William Pitt the Younger, and will be a great asset. Mr. Cameron is also close to Michael Gove, another writer-politician, who is the most articulate British voice of neoconservatism.

However, Mr. Cameron chose not to join Mr. Blair in defending Secretary of State Rice against her anti-American critics. It remains to be seen whether Mr. Cameron, who has modeled himself on Mr. Blair’s charismatic image, also has his substance. The real threat to mankind today is not global warming, but global Islamism. As even Tories concede privately, the only man in British politics willing to do whatever is necessary to defeat the jihad is still Mr. Blair.