Stephen Merchant: The Office boy

But hold on. Extras isn't the creation of Gervais alone. As with The Office, it has been co-scripted and co-directed by Stephen Merchant. Indeed, Merchant was co-writer of the pair's talk show on the London radio station Xfm, and of Channel 4's Meet Ricky Gervais and The Golden Years. He even contributed sketches to The Eleven O'Clock Show when Gervais took over the slot vacated by Sacha Baron Cohen's Ali G.

In fact, as long as Gervais has impinged on the national consciousness Merchant has been there. He rarely steps into the limelight, and often appears to be little more than an extra in the life of the public property that Gervais has become. But without Merchant, it seems fair to say, there would be no David Brent, and the name of Ricky Gervais would go unrecognised beyond Xfm's narrow, cultish audience.

That is where it all began. In 1997 Gervais was head of speech at the newly launched alternative music station, having left his former job as entertainments officer at the University of London students' union. He needed an assistant, and thought he heard something in the radio tapes sent in by a young film and literature graduate named Stephen Merchant. "He called me up," recalls Merchant, "and said, 'I don't know what I'm doing. If you promise to do all the work you've got the job'. As soon as I got there I realised he really didn't know what he was doing and was probably going to get us both fired."

After a while Merchant decided that his job at Xfm was not, perhaps, the stepping stone to an illustrious broadcast career that he had hoped, and took up the offer of a two-year traineeship as a BBC producer (for which he had also applied before the Xfm job came up). But the seeds of his partnership with Gervais had already been sown. "From fairly early on we realised we had the same taste in comedy, the same likes and dislikes," Merchant says. "We built up that common language that means you're already thinking on the same lines before the other person has opened his mouth."

The two had created a character for Gervais called Seedy Boss, originally just to amuse colleagues at the radio station. While at the BBC, however, Merchant made Seedy Boss into a 10-minute short film. Through Ash Atalla, who was later to produce The Office, a copy found its way into the hands of Jane Root, then head of BBC2, and she agreed to fund Merchant and Gervais to work on developing the idea. By 2001 the first series of The Office was on air, and from the chrysalis of Seedy Boss sprung forth the latest in the line of classic British comedy characters - David Brent.

If Gervais is inevitably identified with Brent, the character of his hapless underling, Gareth Keenan, played by Mackenzie Crook, owes something to Merchant. When Crook, a Londoner, was auditioning for the role, he was asked to try a West Country accent. "We think there's nothing funnier than a man from Reading onwards towards Bristol trying to be taken seriously," says Merchant, who at 6 ft 7in shares some of Crook's gangling awkwardness.

Gervais is from Reading; Merchant is from Bristol. He and his younger sister grew up in the Hanham area of the city. Their father was a painter and decorator and plumber who later, like their mother, worked in the community. At the local comprehensive, the young Stephen enjoyed English, drama and history and took part in school plays, performing a comedy turn as a vicar in one show, written by his teachers.

From there he went on to Warwick University, where he studied film and literature - his "two hobbies" - and became involved in a student radio station, writing sketches and DJ-ing in a weekly slot. In his last year he went up to Edinburgh and took part in a sketch show. "We performed to about eight people," he says. "It was not an enormous financial or critical success. But it was great fun."

Returning to Bristol, Merchant "bummed around" for a year or so, temping in a series of tedious day jobs and plucking up the courage to perform stand-up at the city's Comedy Box. "The first week I did well," he remembers. "Then the second week I died on my arse. I realised that stand-up was not that easy after all." He cites Woody Allen, Bob Hope and Eddie Izzard, at the height of his cutting-edge popularity at this point in the mid-90s, as his main influences.

The day jobs, which included a three-day spell in a call centre ("I left because it was too intense," he says), were later to prove very useful in developing material about how ordinary people behave while occupied in mind-numbingly boring occupations. But before long, Merchant's persistence in submitting tapes of his radio work at Warwick and in Bristol paid off, and the call came from Xfm.

Moving to London, the West Country boy was not immediately enthralled with the capital. "I was nervous when I first came, because I was living in Brixton, and I'd only heard of it through the riots." Later he moved to Kennington, but left after there was "one too many shootings" nearby. "There was one outside our local burger shop," he says. "They were crap burgers, but ..." He has since bought a flat in north London where he lives on his own. He chose it, he says, because it is close to the cinema and the supermarket, thus catering to his two most urgent needs.

A love of film is one of the characteristics he shares with Gervais. "Films are the biggest influence on my writing," he says. "I was never interested in writing a traditional sitcom. We wanted to write something that had more of an arc, like a Woody Allen movie, except we could do it over six hours."

We will see more of Merchant in Extras than we did in The Office, where he appeared only once as the "Oggmonster". In the new series, based on the world of the theatrical extra, he plays the agent of Ricky Gervais's character, Andy Millman. Even then, his screen time will be brief. Perhaps this is because fame has come early for Merchant: he is still only 30, Gervais is 14 years older. "There's no race to be on screen," explains Merchant. "I hope to be involved in television for the next 30 years. I don't lie in bed wishing I could be doing Shakespeare soliloquies. Writing, editing and shooting is just such a thrill for me."

For all that Gervais occupies the spotlight, it is clear that he and Merchant have a genuinely equal partnership. "I rarely saw any overruling going on between them," says Atalla. "They had a deal on The Office where if one person had a doubt and couldn't be talked out of it, then it didn't happen." Whenever Gervais is asked about future plans (they have ideas for two further sitcoms), he always mentions working with Merchant. "We'll continue as long as we still enjoy it," Merchant says. "It's a bit like a marriage. We bring different things to the table; although I'm not sure what they are."

As for moving into other areas, less comfortable than comedy, Merchant is content to wait. "If I'm asked on Question Time, maybe I'll be happy to share my views on world hunger," he says. "But at the moment I'm just happy writing knob gags."