Playing Ross Gellar in the popular TV series Friends made him a star and now he is making a name for himself on the other side of the camera. Steve Pratt talks to David Schwimmer about how he is faring at directing his first feature length movie.

Friends is the most important word in David Schwimmer's vocabulary. He owes his fame to the US television comedy series of that name. One of the most popular shows of all time, it ran for ten glorious years and elevated all six of the leading players to celebrity status.

Just don't expect to see Friends reunited, at least not in a continuation or update of that series.

"I wouldn't rule out working with any of those guys again," says Schwimmer, in London for the world premiere of the British-made comedy Run, Fat Boy, Run which marks his feature film directorial debut.

"They're all incredibly talented and I wouldn't hesitate because we all got on great, and I directed all of them on the show as well. We would never do that show again. But they're terrific and I'd never hesitate to work with them again."

Schwimmer is clearly a man who values friendship. Run, Fat Boy, Run finds him working with another friend, Shaun Of The Dead and Hot Fuzz star Simon Pegg. He's played a big part in shaping Schwimmer's first movie behind the camera.

The pair knew each other from Steven Spielberg's Second World War series Band Of Brothers. "Because of the character I was playing, I was really anti-social during that time. I didn't really make an effort to kind of bond with anyone," recalls Schwimmer.

He and Pegg became - that's right - friends when reunited on a movie called Big Nothing. The film didn't make much of an impact in cinemas, but the pair hit it off. When Schwimmer needed someone to Anglicise a movie script he'd been attached to for some time, he turned to Pegg.

That became Run, Fat Boy, Run - the story of an unfit chap who decides to run a London marathon to prove to the girl he jilted at the altar that he's not so bad after all.

"It was supposed to take place in New York around the marathon, and I was pitching actors that they (film bosses) were saying 'no' to - like 'we can't make a film with Philip Seymour Hoffman or Paul Giamatti'. I just thought that they didn't want to make the movie, I couldn't understand.

"Suddenly, the script was optioned by Material Entertainment, whose mission is to make films in London. At that point I was already a year-and-a-half into trying to get the movie made and then I thought now I hav to find someone to rewrite the script to Anglicise it and find someone to star in it.

"All of this was going on while Simon and I were working together on Big Nothing and having a blast. I don't know if it was me or someone else who suggested him but, as soon as the idea occurred, I thought it was a perfect fit.

"So I called him and said, 'take a look at this, what do you think about rewriting it, Anglicising it and starring in it and working together?'.

"I think we'd had such a good time working together that we thought it would just be fun and kind of easy."

There was one drawback. New York-born Schwimmer had spent four months doing a play in London followed by shooting a movie in the UK, so he wasn't excited about spending the next year of his life over here too. "It was just being away from home. But the only way I got my head around it was by thinking that if Simon were to do it, then it would be worth the time."

The pair are together again the morning after the night before, feeling slightly the worse for wear after the previous night's premiere party but not neglecting their promotional duties.

Schwimmer has a lot riding on its success. He's always wanted to direct a feature film after directing theatre and episodes of Friends. Because a movie takes a year to do, he had to wait until he was finished with the TV series.

"I started looking for scripts and read many of them. This was the funniest thing I read, but I was also surprisingly moved by it. I was really excited by the challenge of trying to capture the tone of that script on film."

Schwimmer would like to direct again. In the post-Friends world, that may be his best bet. Like his co-stars, the films he made in breaks from shooting Friends were mostly unremarkable. They may have been stars in one of the best-loved series on TV, but it seemed the Friends cast couldn't crack the movie market.

His background was theatre, which he studied at university and, in 1988, co-founded Chicago's Lookingglass Theatre Company with seven other Northwestern University graduates. He's acted in and directed many productions with the group.

He was in a good position making Run, Fat Boy, Run to compare and contrast the American and British film industries. He didn't notice too many differences, finding crews top notch in both countries.

"I've mostly worked in Los Angeles, a little in Chicago and again on that side of the camera everyone's just great. It depends on the tone set by the producers and the director and the star of the movie. The crew really picks up on a lot of that, they feel like we're all having a good time and are getting along.

"I try and make a team effort and that's why I've had good experiences on both."

Despite the "very modest budget", Schwimmer, the director, puts a gloss and sheen on the movie, with imaginative use of familiar and not-so-familiar London locations.

But the capital is an expensive city in which to shoot a film, especially one like Run, Fat Boy, Run which filmed all over the city. "We had 50 locations and at each one we had to deal with security, police, traffic and tourism," he says.

"Each location cost a fortune, especially when we were shooting in the city. The unions are incredibly strong - rightly so - but because of that the cost of having ten extras here was the same as getting 50 or 100 extras outside the city for the same price.

"There were challenges throughout, but the producers were great. They tried to keep as much of it out of my way as possible. They dealt with most of the red tape although most days there were problems involved."

One of his biggest challenges as an actor must have been having a seven-year-old boy, Matthew Fenton, as one of the key characters. Pegg plays his father in the film. "We did everything just to get to know Matthew and make him feel comfortable. We played with him and made him a friend," he says.

"Again, it's all him really because he's wonderfully mature. He's a kid, but at the same time he's a professional. He showed up knowing every single one of his lines, and everyone else's lines too.

"He knew we'd like to play with him, but as soon as he had to work, he took direction and was immediately focused."

* Run, Fat Boy, Run (12A) is now showing.