After what promises to be a royal welcome at the White House on Monday, what will Elizabeth II and the president talk about in private?

I would be surprised if the name Tony Blair does not come up in their conversation, if only because both President Bush and the queen almost certainly know something that hardly anybody else does: the date of Mr. Blair’s resignation. Elizabeth II is already preparing for the 11th prime minister of her 55-year reign.

Ten years to the day since he came to office, Mr. Blair gave notice on Tuesday that he will name his resignation day next week. “I’ll say something definitive then,” he said, prolonging for a few more days what has already been the longest goodbye since the queen’s first prime minister, Winston Churchill, when he retired in 1955.

Ever since Mr. Blair first spoke of resigning on the day of a minor heart operation in 2004, he has been seen by the press as a lame duck. Today, his party is expected to be trounced in the elections to the Scottish Parliament, one of Mr. Blair’s legacies.

But the Scots are not the only ones to bite the hand that has fed them. The Labor Party, in which atavistic anti-Americanism has replaced the socialism he jettisoned, cannot wait to see him gone. Mr. Blair’s “big tent,” the electoral coalition that once embraced everyone from Leftist lobby groups and ethnic communities to patrician Tories, has long since collapsed.

Seen from America’s point of view, however, Mr. Blair’s resignation looks odd. He is better known and better liked than just about any other foreign leader. The same viewpoint holds true even when this resignation is considered from a historical perspective. When Churchill left the stage, he was 80 years old and had suffered two strokes. Most leaders don’t have the luxury of choosing their moment to depart: defeat, illness, or death force their hands. But Mr. Blair is still in good health for a man in his mid-50s.

So why is he going? The one word answer is: Iraq. As far as political mistakes in the conduct of the war, the buck certainly stops with Mr. Blair, no less than with Mr. Bush. Neither has ever denied responsibility for errors.

But is it fair to condemn the president and the prime minister for the decision to go to war at all? As America’s presidential campaign shows, it’s not that simple. In Britain, as in America, most of the administration’s critics actually supported the war — before, during, and for a long time afterwards. They are the fair-weather hawks whose miraculous metamorphosis into doves is unlikely to fool all of the people all the time.

If they had known then what they know now, they, as in the likes of Hillary Clinton, would have done things differently. But these defeatists have the singular distinction of being unwise after the event. They were right to heed the warnings about Saddam Hussein then, but they are wrong now to play down the warnings about Ahmadinejad. And it is the same critics who now oppose robust measures to deal with the enemies — principally Al Qaeda and Iranian-backed Shiite militias — who are trying to make Iraq ungovernable.

The war against terror is far from won, but at least it is no longer being lost by default, as it was before September 11. If Mr. Blair deserves criticism, it is not for taking the fight against the Islamofascists in Iraq, but for doing too little, too late to confront the jihad in his own back yard.

Two years ago, after the July 7 bombings in London, it dawned on a horrified nation that Britain had become not only one of Al Qaeda’s main targets, but also one of its main sources of recruits.

The British are still coming to terms with the consequences of the multicultural policies pursued in their name over the past generation. The unspoken fear is that Britain may never again constitute a nation united and at peace with itself.

The British, like the rest of Europe, have been in denial for decades about the infiltration of Islamist organizations, which recruit young men for jihad. Sharia courts have been quietly set up all over Britain and enjoy the tax status of charities. Readers of this column know all about the creeping Shariaization of Britain, but the political class is only now beginning to grasp the true nature of groups such as Hizb-ut Tahrir, which works for the restoration of the Caliphate and the “liberation” of Muslims. They go about their work of poisoning young minds with impunity.

Polls indicate that Mr. Blair’s likely successor, Gordon Brown, is, even before he takes office, the most unpopular politician in Britain. He will be even more unpopular before the voters throw him out, probably in two years’ time. It looks increasingly likely that the Blair era will, after a short Left-wing interregnum, be followed by a sharp move to the Right.

For once, Britain is moving in the same direction as France. If Nicolas Sarkozy triumphs this Sunday, he will take office just before Mr. Blair exits Downing Street — undefeated, unflinching, and unrepentant. Let us hope this changing of the guard will not leave European civilization without a worthy champion.