The economist John Maynard Keynes was wrong about many things, but he was absolutely right in the last sentence of his “General Theory”: “But, soon or late, it is ideas, not vested interests, which are dangerous for good or evil.” That is why for me the most interesting event this week, though it warranted only a paragraph in the London Times, was the appointment of Matthew D’Ancona as editor of The Spectator.

The 70,000 readers who buy this right-of-center weekly magazine comprise much of the British political and social elite. With its parties and lunches, its capacity to create mischief for friend and foe, the “Speccie” has been synonymous with the lighter, more frivolous side of conservatism. But if he plays his cards right, Mr. D’Ancona may well have as great an influence on the political climate in this country as any of the politicians he writes about.

Not that the politicians have been idle; they never are if there is a chance to meddle. On Tuesday, the House of Commons voted by a large majority, and against the government, for a total ban on smoking in public places. So New Yorkers will feel even more at home here when they come next year to find that London hotels, pubs, restaurants, and even private clubs have become smoke-free zones.

The same parliament that is so zealous to extend the long arm of the law into private clubs is, however, much more jealous of personal liberty in the war on terror. MPs of all parties have tried to thwart Tony Blair over his latest anti-terrorism bill by passing a series of wrecking amendments. Yesterday they only just failed to prevent a ban on the glorification of terrorism. Conspicuous in this strange alliance of libertarians and Islamists has been the Conservative Party.

Meanwhile, the gossip in Westminster is that the country is now being run by a “dual premiership.” Mr. Blair has promised that before the next election, which will probably be in 2009, he will step down in favor of his longtime rival Gordon Brown, the Chancellor of the Exchequer. Nobody knows exactly when the handover will take place, nor whether Mr. Brown will, as he hopes and expects, inherit Mr. Blair’s mantle without a contest.

Last week, however, the Labor Party suffered a surprise defeat in a by-election in the Scottish town of Dunfermline, where Mr. Brown happens to live. The chancellor had campaigned hard there, to no avail. The by-election was won by the Liberal Democrats, a small third party that happens to be leaderless and reeling from scandals involving alcoholism and homosexuality. Losing to such losers is not a good advertisement for Mr. Brown. If he is so unpopular in his own back yard, people are asking, how will he hold together the broad coalition of support that has enabled Mr. Blair to win three elections?

All this should be good news for the Conservative leader, David Cameron, who is taking paternity leave after his wife gave birth to their third child. But he, too, is feeling bruised after Mr. Blair humiliated him in Prime Minister’s Questions last week. Unwisely, Mr. Cameron accused Mr. Blair of flip-flopping. A triumphant Mr. Blair suddenly produced a leaflet from the Dunfermline campaign in which Mr. Cameron described his party as “liberal Conservatives” and tried to minimize the differences on Iraq between himself and the anti-war Liberal Democrats. It was game, set and match to the Prime Minister, cartoonists and satirists had a field day, and the “flip-flop” label was instantly attached to Mr. Cameron.

The impression that the British Conservatives are incorrigible opportunists has been firmly entrenched in the White House ever since the previous Tory leader, Michael Howard, tried to exploit anti-Americanism by flip-flopping on Iraq, thereby giving ammunition to President Bush’s opponents. Karl Rove let him know that he was persona non grata, creating the unprecedented and unedifying spectacle of a Conservative leader who was not on speaking terms with a Republican president.

In an effort to restore good relations with the Bush administration, Mr. Cameron dispatched a delegation to Washington this week to meet Mr. Rove and other senior figures, including Senator McCain and Federal Reserve Chairman Ben Bernanke. The Conservatives sent their A-team: foreign affairs spokesman William Hague, defense spokesman Liam Fox, and finance spokesman George Osborne. Mr. Cameron is eager to establish his own Atlanticist credentials, and no doubt hopes that this visit will pave the way for him to meet the president himself.

If Mr. Rove is wise, he will issue that invitation. But it will take more than a handshake in the White House to destroy the virus of anti-Americanism that has spread throughout the British body politic, including the Conservative Party. That is where The Spectator could make a real difference.

For the intellectual climate is largely created by journals such as this. It was Archimedes who declared: “Give me but one firm spot on which to stand, and I will move the earth.” The organs of neoconservatism – mostly small circulation journals such as Commentary or the Weekly Standard – were the levers that moved the mightiest nation on earth, the United States, to deploy the power of ideas in the war on terror. George W. Bush would not have been elected, let alone re-elected, but for the influence exerted by conservative ideas on the American public.

In Britain, there has hitherto been no comparable renaissance of conservative thought. Whether Matthew D’Ancona can single-handedly precipitate such a revival remains to be seen. But he is eminently qualified for the task.

Only 38, he has the inquisitive mind of a first-class Oxford historian, the inside knowledge of a political columnist, and the instincts of an intrepid reporter. He has a clear grasp of the danger to the West posed by radical Islamists, and that it is in Britain’s interest to support the United States and Israel. He is not a partisan Tory, still less a member of Mr. Cameron’s Notting Hill set, and gives praise to Tony Blair where it is due. He thinks for himself, is principled and intelligent – everything that the Conservative Party has manifestly failed to be in the post-Thatcher era.

I don’t agree with Mr. D’Ancona about everything, but if anybody can shake up the Tories, he can. I am confident that he will stick to his guns, too. In an age when editors may get fired or even murdered for publishing a cartoon, Mr. D’Ancona may need to be very brave indeed.