London ? Political squalls have drenched Gordon Brown this October, already as cruel a month as the new prime minister hopes ever to encounter. He suddenly struggles to convince voters that nothing more serious than autumn rain is falling on his new Labor government – not a shower of acid that will erode Brown’s reputation and Labor’s hold on power.

His efforts to regain momentum and public confidence are important for Americans too. The British prime minister is arguably the most important foreign ally that an American president has. The prime minister’s political strength is a matter of U.S. national interest.

Without Winston Churchill, Margaret Thatcher or Tony Blair, the political fortunes and historical images of Franklin Roosevelt, Ronald Reagan and George W. Bush would have been quite different.

But history’s highly developed sense of irony is on display in the change from Blair to Brown. The London reins of the special relationship are now held by a leader who has far more firsthand knowledge of the United States and Americans than Blair ever did. But Brown the Americanist arrives at 10 Downing Street at a time when any British leader seeking to regain confidence is obliged to attenuate the relationship and distance himself from the much reviled Bush.

Brown began that process with a Camp David visit this summer in which he adroitly avoided headlines back home and the warm embrace that Bush customarily fastened on Blair. The Bush administration, with friends abroad in short supply, desperately pretended not to notice Brown’s studied aloofness.

But Brown’s announcement last week of new troop withdrawals from Iraq – with a goal of shrinking the British force to 2,500 by next summer – again underlined that he is not Bush’s creature, even though the reductions are portrayed by the government here as routine and nonpolitical.

Brown, a close friend of former Federal Reserve Chairman Alan Greenspan and other politically active Americans, has routinely vacationed on Cape Cod in recent years. But after taking over from Blair a little over 100 days ago, Brown stayed home this summer and watched his popularity soar while he calmly put out a series of national brush fires.

He had managed Britain’s economic boom as Blair’s chancellor of the exchequer. His very dourness and nervous intensity were hailed as welcome contrasts to the supremely self-confident Blair, a political rock star who was deemed to have used up all his magic in the service of Bush.

Brown and some of his advisers could not resist an opportunity to toy with – and hopefully destabilize for another decade – the opposition Conservative Party. So they set in motion machinery for a surprise autumn election, then abruptly pulled back in disarray when the Conservatives launched their own surge operation that turned the polls against Labor.

Instead of the image of the decisive and caring manager that he wanted to project, Brown suddenly appeared to be as manipulative and opportunistic as Blair – only not as deft. Brown’s effort to convince Britons that he represented progressive change after 10 years of Blair was left in shambles by bruising exchanges with the media, Labor Party dissidents and the Conservatives in Parliament.

Washington must now cope with Paris being the new London. The rock-star, high-energy politics and charisma that were once Blair trademarks have migrated across the English Channel to France. Nicolas Sarkozy in his first 150 days has tried to narrow, not widen, France’s strategic distance from the United States. Sarkozy is now the European leader who incarnates change, ambition and an almost hubristic optimism.

Because of changing personalities at the top and changing global circumstances, Britain enters a period of new caution in economic and political affairs while France looks for opportunities to be daring. Sarkozy’s activism has already shaken up other European governments that fear he goes too far too fast, and the Frenchman’s determination to change things will reach across the Atlantic in unpredictable ways as well.

Throughout the Blair years, London was always a sunny place for this American visitor, even when it was actually raining or when the political weather turned stormy, as it finally did for Blair. Even then, Blair pitted his endless enthusiasm against the listless, embittered worldview of Jacques Chirac and other European leaders to provide a rallying point for the belief that things could be made better.

With economic growth starting to flag and voters projecting their own fickleness onto their new prime minister, Brown may well be wondering if Blair has used up all the sunshine that was available in British politics.