Anthony Neilson: Promise? I was showing that years ago

At 36 and already a hit, playwright Anthony Neilson questions his 'potential'

He's already written and staged one of the plays of the year (Stitching) and hopes, before 2002's done, to repeat the feat (with The Lying Kind, opening at the Royal Court this week). He kick-started the trend for explicit theatre that dominated the Nineties. He's had successes de scandale on the West End. No wonder Anthony Neilson's a bit confused to be nominated, a fortnight ago, as Most Promising Playwright at the forthcoming Evening Standard awards. "What promise is it that I'm not fulfilling?" asks the dismayed 36-year-old. "I can only assume that it's the promise to make somebody some money."

If so, his pedigree suggests it's a promise that it may take some time to fulfill. An instinctive outsider, Scottish-born Neilson came to prominence as the writer of dark psycho-sexual dramas for the London Fringe. "In-yer-face theatre" poster-girl Sarah Kane was directly influenced by Penetrator, which Neilson launched at the Finborough Theatre in Earl's Court; at the same venue, he also directed an early version of Mark Ravenhill's Shopping and F***ing. Under the auspices of the Red Room theatre company, he took his porn-infested love story The Censor, whose heroine defecates on stage, into the West End. The following year, 1999, he wrote and directed his first movie, The Debt Collector, with Billy Connolly and Ken Stott.

So his current prominence – hisNight Before Christmas is also being revived, with ex-EastEnder Patsy Palmer – is nothing new. "I go in boom and bust cycles," he says. "This isn't the second coming, it's about the fourth." His stock's most recent rise came with this summer's terrific Red Room/Traverse Theatre hit Stitching, a characteristically brutal yet tender account of how a bereaved couple submit to their dark sexual impulses. With the news that his next play would be opening at that famed centre of sensation, the Royal Court, theatregoers braced themselves for more blood – and semen-stained postcards from the edge.

No one expected a farce. "I shouldn't use that word," says Neilson. "If I start thinking that I'm working in this huge lineage of farce, then it gets very intimidating." But farce his new play, The Lying Kind, undoubtedly is – there's even a vicar locked in a wardrobe. In his defence, Neilson argues that, "after Stitching, this seemed the most radical thing I could do."

Not only is The Lying Kind a farce, it's one that eschews the subject, sex, from which Neilson's dramatic gaze has seldom before flinched. But sex, says the playwright, is unsuitable for laughs. "I'm not sure about British culture and that thing about sex being really funny," says Neilson. "I've never thought sex was that funny."

Instead, The Lying Kind (inspired, says Neilson, not by stage farce but by Fawlty Towers-style sitcoms) focuses on death – in particular, a young woman's death on the road while travelling home for Christmas. The play begins with two policemen who are too cowardly to break the news to the woman's ageing mum and dad.

Its genesis was in a relationship Neilson once had with a woman who "constantly lied to me in an attempt to protect me. I wanted to look at how we damage people in the way that we lie to them to be kind to them." He admits, however, that that theme is now deeply submerged beneath the blackly comic shenanigans on the play's surface.

"However hard you try," he says, "farce just doesn't support overt depth. I love to be in a theatre where everybody is laughing," he says, "and I hope they will."

If that sounds like a tame ambition for a man with his incendiary track record, fear not – Neilson still swears, "I will never go over to the mainstream." He sees the Most Promising Playwright nod as further evidence of a "terrible snobbery" towards the Fringe, where he has spent much of his theatrical life.

"I find theatre much more stimulating with an audience of 60 concentrating people," he says. "I never want to be at the stage when I always have to work in monolithic venues." There's a similar snobbery towards his unorthodox working processes (he prefers to write during rehearsal) and his habitually transgressive subject-matter. "These people think, 'When's he going to do a grown-up play?'" he says. "There's a huge pressure to do that. It is reinforced constantly in the language and the way they talk about you. 'Promising...' 'Interesting...'"

Unhappily for those keen to see this enfant terrible grow up, the success of Stitching has, The Lying Kind notwithstanding, staved that off for a few years yet. Of Stitching's success, he says, "I was very heartened to find that this more visceral theatre is still a valid area of work. It wasn't just a phase. Of course, you can look at Sarah [Kane]'s death as having closed it off. It makes for a cute little period. But it's good to be able to say, 'No, this wasn't just a trendy thing, it is actually one of the ways in which I express myself.' These are themes that I'm genuinely interested in. It's nice for me to be able to go: 'I'm not mellowing, I'm not changing.'"

'The Lying Kind': Royal Court Downstairs, London SW1 (020 7565 5000), previewing, opens Friday, to 11 January. 'The Night Before Christmas': Riverside Studios, London W6 (020 8237 1111), 3–30 December