Attempts to take British television shows across the pond have been disastrous and the lastest export, saucy comedy Coupling, may prove to be too sexy for a US audience.

Americans are a funny lot when it comes to watching versions of British comedy shows tailored to their sense of humour. Take Snavely, a comedy set in an off-highway hotel run by a manic manager and his domineering wife, with the help of a bellhop who barely spoke English. The series progressed no further than the pilot episode.

Undeterred, 20 years later they made Amanda's. The manager of a hotel overlooking the Pacific was a woman but just as formidable as her male counterpart in Snavely. Only nine of the 13 episodes were transmitted before the series was cancelled.

Then, in 1999, they hoped for a case of third time lucky. Payne, with John Larroquette running the hotel as Royle Payne, was screened - and failed to find any greater favour that Snavely or Amanda's.

All three were attempts to turn classic British comedy Fawlty Towers into a hit US TV series. The Americans never did find the right formula and it's a lesson those transferring the BBC's saucy comedy Coupling to the major NBC network would do well to heed. What's a hit in Britain isn't automatically a hit in America.

Much is being made about Coupling, only a modest hit with a couple of million viewers on BBC2, being "the new Friends" - possibly because the network needs a replacement for Friends, ending soon after nine seasons.

Coupling, which also charts the sex lives of thirtysomething male and female acquaintances, seems the obvious substitute. The big worry is that the scripts, by Steven Moffatt, are too sexy for the notoriously prim big networks. With advertisers to satisfy, they shy away from the bad language and explicit sex that cable channels exploit in shows like The Sopranos and Sex And The City.

American viewers have already been exposed to the rude, bawdy antics of Coupling on cable station BBC America. The 33 million homes that take the channel are used to seeing outrageous things, as it shows C4's So Graham Norton. "If you're an American flipping through hundreds of channels and you come across us, you're probably thinking, 'hmmm, BBC America, that'll be some nice Jane Austen piece'. Then there's me with a big dildo," says Norton.

BBC America has been showing Coupling in a late night slot and advertising it as "a very grown-up Friends".

The more conservative, major networks are a trickier proposition. Writer Moffatt and his producer wife Sue Vertue are closely involved in taking Coupling across the Atlantic. They say they've been told by NBC to keep as close to the original as possible, and not asked to tone it down.

The setting has switched to Chicago and completely re-cast. The first episode, according to reports, contains a hunt for a condom and a couple trying to have sex in a restaurant toilet.

Perhaps they'll be allowed to break barriers. Jokes about oral sex and erections aren't commonplace on network TV. Neither is nudity. Friends, like most US comedies, talks around such topics with being explicit.

NBC Entertainment president Jeff Zucker admits that Coupling is being shown after 9.30pm because of the raunchy content. "It's a provocative show. There will be no other comedy on broadcast television like it," he said.

The US version of Coupling may get away with playing dirty, but there's no guarantee audiences or the all-important advertisers will like it. What does matter for our TV industry is that US versions of The Office, Father Ted and The Kumars At No 42 are in the works.

Even the sitcom The Savages, poorly-received on BBC1 a couple of years ago, is being developed for a US series by Fox Television. Its writer, Simon Nye, knows that the record of Brit-coms abroad isn't good. His BBC hit Men Behaving Badly reached US screens in a toned-down, politically-correct version and was panned.

Sometimes matters don't progress beyond the talking stage. Sit-com star Roseanne Barr bought the rights to Absolutely Fabulous but, after several attempts to set up the series in the US, admitted defeat.

There are exceptions. Til Death Us Do Part's Alf Garnett became the equally-bigoted Archie Bunker in US hit All In The Family, and flat-sharing comedy Man About The House had a successful outing as Three's Company.

Drama has had some success too. Cracker, without Robbie Coltrane, enjoyed a reasonable run in a US version - which was then sold back to ITV.

Ground-breaking Queer As Folk was able to retain a high level of sex and nudity because it was shown on a cable channel. The most profitable British exports have been game shows and reality formats. Formulas such as Big Brother (not one of ours) and Pop Idol are big business around the world.

The BBC is reckoned to have made £50m from selling The Weakest Link to the US, and ratings for Who Wants To Be A Millionaire? took off on the other side of the Atlantic. Ironically, Survivor was bigger in America than Britain.

Channel 4 is finding rich pickings remaking reality shows Wife Swap and Faking It with American participants. The BBC's Changing Rooms became Trading Spaces.

The list is getting longer by the minute. And, who knows, one day, they might even find a way of making Fawlty Towers attractive to American audiences.