Heard the one about the US sense of humour?

According to a certain Professor Christie Davies, whose lecture to the Society of International Humour Studies was reported in Monday's Independent, the cornerstone of British humour, its irony and self-mockery, is slowly being eroded by America.

According to a certain Professor Christie Davies, whose lecture to the Society of International Humour Studies was reported in Monday's Independent, the cornerstone of British humour, its irony and self-mockery, is slowly being eroded by America.

He cited Disney's treatment of Winnie-the-Pooh as an example of gentle British wit, if not irony, being obliterated by Hollywood. Which struck a chord with me. Obviously, I have other concerns, such as rising car crime and global warming, but it has troubled me for some time that Piglet speaks to my children with an American accent.

Professor Davies, incidentally, holds the chair of sociology at Reading University, making me wonder whether he sometimes whips the chair away just as someone is about to sit down. But that would be slapstick, and slapstick - pace fans of Charlie Chaplin and Harry Hill - is not what Brits do best. At irony and self-mockery, however, we are world-beaters.

Professor Davies thinks they are a good thing, a sign of self-confidence. But he fears that they are being watered down in pursuit of a transatlantic audience. British humour is becoming a poor imitation of American humour, and Americans do their own humour better, he says.

Amen to that. In recent years British television producers have ended up with egg on their faces, to go with the polenta on their chins, trying to replicate sassy American sitcoms. Mostly the results have been spectacularly dismal, none more so than Brighton Belles, ITV's 1993 version of NBC's The Golden Girls, and BBC2's current vehicle for Rhona Cameron, the very unfunny Rhona.

In fairness, though, humour's transatlantic crossing can be perilous in both directions. Some years ago, an American network sought John Cleese's permission to remake Fawlty Towers. A battalion of writers was attached to the project, and Cleese waited with baited breath to see what they would throw up.

After three days brainstorming in some Burbank basement, they emerged to tell Cleese: "We've decided to take the Basil character out." They probably mispronounced Basil, too, rhyming it with Hazel. Because the most basic pitfalls are linguistic ones.

When one of our finest TV comedy writers, Simon Nye, wrote a pilot for NBC about an animal-hating vet, he was inundated with long-distance calls pointing out that: "We don't say budgie over here, asshole" - or words to that effect. Moreover, the Americans found even his subject matter a little worrying, to the extent that one executive, perhaps the same one who dealt with Cleese, suggested: "Can't we make it a comedy about a vet who loves animals?"

We don't understand each other, never have and never will. It is not so long since I read in The New York Times an enthusiastic account of a long weekend in London. The writer expressed genuine disappointment, however, that there had been no sign of "the fabled London pea-souper". She was doubtless surprised, also, not to be chased along a cobbled street by Jack the Ripper.

But ignorance travels in both directions. The writer Anthony Holden, explaining why he is leaving "philistine and xenophobic" Britain to settle in the home of the brave and land of the free, committed the common error of mistaking Manhattan for America.

And to back up his withering assault on Britain, not to mention his fervent republicanism, he quoted John Updike's observation in The New Yorker: "Without their crowns and coronets, how could the English be distinguished from the Icelanders?"

It's a fair point. And a pretty stout argument for keeping a tight hold on those crowns and coronets. But perhaps I'm just being ironic and self-mocking.