Taking a successful TV comedy series onto the big screen can be a dangerous game. But, as the League of Gentlemen tell Steve Pratt, they're confident their film will appeal to the widest possible audience - as no-one will know what's going on.

The history of cinema is littered with TV comedy series that have tried and failed to transfer to the big screen. The award-winning The League Of Gentlemen - namely Jeremy Dyson, Mark Gatiss, Steve Pemberton and Reece Shearsmith - were determined not to let it happen to them.

They remembered only too well how what was funny on the small screen seemed desperate in a feature. Some TV shows simply did the same thing only at greater length. British cinema went through a period of cheap and cheerful transfers including On The Buses, Man About The House and Steptoe And Son. Most felt the need to take familiar characters out of their usual environment in order to raise laughs, such as sending the Grace Brothers staff on holiday to Spain in the Are You Being Served? movie.

Over the past decade, the writer-comedians in The League Of Gentlemen have moved from radio to TV and a theatre tour. Only film remained to conquer, an obvious move for performers with a keen, movie buff-type interest in cinema. "We wrote the film on spec. We didn't want anyone looking at it halfway through and trying to shape the film," says Pemberton.

They've always tried to push into another direction and not tread water, continues Shearsmith. "That why in each series we've tried to make a bold move, especially with the third TV series, which was very different from the first two," he says. "Inherently we want to keep doing what people like, but the film allows us to do something we've never been able to do before."

The League Of Gentleman's Apocalypse is nothing if not ambitious as the story travels through three parallel realities as three of Royston Vasey's most famous local residents - escaped convict Hilary Briss, camp German exchange teacher Herr Lipp and broken-down white collar worker Geoff - seek out the writers after learning of plans to kill off the characters they've created. A 17th century horror movie and, as the title suggests, the Apocalypse, also feature in the multi-layered narrative.

Other characters from Royston Vasey put in appearances too, although Dyson reamins the fourth, unseen member of the League. He's played by actor Michael Sheen.

Fans will be expecting to see their favourite characters so deciding which ones would appear was tough as, between the three of them, they've done around 100 characters in the series so far. "When it came to deciding the main group of characters to carry the story, it kind of chose itself really. The more extreme characters didn't seem able to exist in a real world and do what we wanted them to do," says Pemberton.

"It gave us the option to explore characters we knew a little bit less about and felt less spin-offy. Because we didn't want it to appeal to fans only, we thought it was more universal if we opened it out."

Oddly enough, the hardest parts to write were themselves in the scenes in which Mark, Reece and Steve appear. "We experimented with a different way of writing for ourselves and suggested giving ourselves different names so it wouldn't be so difficult. But at the back of your mind you know that Kevin is really you, so we struggled with that," says Pemberton.

'We thought we might give ourselves comic characteristics, but it just absolutely fought the whole idea that it's the other characters' journey that you're interested in. So we just had to become sort of phantoms really," continues County Durham-born Gatiss.

There will, of course, be people out there who've never seen or heard The League Of Gentlemen before but a multi-million pound movie needs to attract a broad audience to have any chance of making money. Initial audience reaction indicates they've pulled off this difficult feat.

"It's a funny thing, we've had some responses from people who know the series who were worried they'd get it but no-one else will," reports Gatiss. "But a lot of people who haven't seen the TV series have no problem because we strove very hard from the beginning to make it very 'gettable'."

Shearsmith says you couldn't rely on however many million people who watch the TV programme would watch the film. They wanted it to be a comedy film in its own right.

For all that, Apocalyse is obviously a spin-off film. "It has to be because that's how we got the money," Gatiss points out. "And you've got to know that in the pre-publicity everyone's going to say, 'and a certain amount of people might be put off because they've never seen it'. We like to believe you could completely get it, there's no reason why you shouldn't."

And Pemberton adds: "If we'd carried on the story of the TV programme, then people who hadn't seen it wouldn't have had a hope. By taking the characters out of Royston Vasey on this journey which ends up back there again, fans and non-fans are in the same position. No-one knows what's going to happen."

The TV show has been successful all over the world, including in Poland, Finland and Eastern Europe. They don't know how Herr Lipp has gone down in Germany. "I expect they've made him Austrian or Swiss, done a Manuel on it," says Pemberton. Gatiss volunteers the information that in Japan the series is called Psycho-ville.

They first realised that the Royston Vasey locals had taken on a life of their own during their first stage tour in 2000. The show opened with Tubbs and Edward rising from the ashes of the Local Shop and "there was this eruption of cheering and love for those characters", Pemberton remembers. "That's very different from individual people coming up and saying they liked the show or reading a nice review. This was a mass of people. Wherever we went in the country, particularly north of Watford, you got a massive response, especially from places like Newcastle and Manchester."

Gatiss says that in being on TV for six years you create a body of work that alters the public's view of you. "It's very different to just being the catchphrase of the day and then the series is gone again. If you keep coming back, it builds so we get much more recognition now than we used to," he says.

League members have known each other for 20 years and have been working together for ten. When they're not Gentlemen, they're busy on individual writing and acting projects. "I've always thought we've been outside the comedy world, not deliberately, but we regard ourselves as actors. Not in a snooty way, but we've come from that background and not from the comedy stand-up circuit," says Shearsmith.

Gatiss has not only taken acting roles but also wrote an episode in the new Doctor Who series. "I just did The Quatermass Experiment and saw a review which said 'Mark Gatiss, reminding us that he's a straight actor, not just a comedian'. Not just - there's always this slightly pejorative air.

"Comedy is very tough. Curiously, it's like the poor relation to the idea of straight acting but it's absolutely as valid," he says.

The League Of Gentlemen plan to tour again later this year with a pantomime-style theatre show. The BBC has asked them to do another series but they seem keener to do another film, provided the first does well. "We've always set our own agenda. It would be a very dangerous thing to set deadlines that we have to meet. We've never done that. We've always thought carefully about what we want to do next," says Pemberton.

* The League Of Gentlemen's Apocalypse (15) opens in cinemas on Friday. The League Of Gentlemen Complete Collection is released on BBC DVD today. Repeats of the TV series continue on BBC2 on Tuesdays at 10pm.