Tim Burton and Helena Bonham Carter: Up for a laugh

We may dress in black but we're a fun couple, honestly, Tim Burton and Helena Bonham Carter tell Roger Clarke

It's a fair point. The film concerns a gloomy and neurasthenic young man, Victor (voiced by the Burton regular Johnny Depp), pushed into marrying the well-heeled daughter of impoverished aristocrats (grotesque figures voiced by Albert Finney and Joanna Lumley) who think Victor is common as muck.

Intimidated, Victor goes for a walk and before you know it he's got engaged to a dead woman by mistake: the corpse bride of the title. She's voiced by Burton's partner and the mother of his son, Helena Bonham Carter - the great-granddaughter of Herbert Henry Asquith, the 20th-century prime minister, with sundry hereditary peers and Rothschilds among her near family. "Are you saying," Burton coughs and gargles, pushing his thick-rimmed tinted spectacles up his nose, "it's all based on her family?"

Burton is thoroughly entertained by the notion (later, I read that Depp's acting style with him is a constant effort to make him laugh). Then he seems to collect himself. "No," he says. "I don't know much about her family. We're from such different backgrounds. I'm kind of white trash and she comes from lord and lady whatever - so it's kind of a funny difference, you know."

It is one of the most unlikely of combinations, after all. He's a Californian hipster and B-movie-loving goth; she's a public-school girl who was for a long time a kind of Merchant Ivory pin-up, forever gadding about in frocks and twirling parasols. But after Burton worked with Bonham Carter on Planet of the Apes, they began dating. And, if cursory impressions are anything to go by, they clearly adore each other. They seem like two big kids having a whale of a time, both during their interview and during the premiere.

Burton talks about the five years it took to make the movie, and about how he doesn't have the patience to animate any more and relied heavily on his co-director to do the day-to-day work. He oversaw the footage on a high-speed link from Pinewood, where he was directing Charlie and the Chocolate Factory. Depp, who stars in both films, would often work on Charlie by dayand then step into Victor's animated shoes in the evenings.

"I've always been misrepresented," Burton concludes. "You know, I could dress in a clown costume and laugh with the happy people but they'd still say I'm a dark personality."

Bonham Carter, too, feels her image is something foisted on her by other people, though she doesn't help matters by admitting to me that she used to think she could "go back in time if I got inside the television and dressed up in costumes", and that her first crush was on "Jeremy Irons in Brideshead Revisited - I kind of stalked him, scary, then I met him once and it was all over."

Burton and Bonham Carter now live in Belsize Park, in north London, where they are raising their two-year-old son, Billy. She shows off his picture in a necklace round her neck (she's taking him to the beach after she has finished here - "chuck him in, see if he sinks," she snorts).

She did the voiceovers for both Corpse Bride and Wallace and Gromit: the Curse of the Were-Rabbit as she was pregnant, traipsing up to Hampstead to lay down the soundtrack while Burton was making Charlie and the Chocolate Factory at Pinewood. It wasn't until she told Burton that she was doing Wallace and Gromit that he piped up: "Hang on a minute - I was going to ask you to do a stop-motion picture." She laughs. "So it's like London buses: two come along at once."

How did he direct her in the movie? It's now the fourth they've done together. The dynamics between couples in such situations can be tricky. "Well, he wasn't always there," she recalls, "but he was there for the last session - he just told me to keep my voice up, since my voice is naturally quite low and he wanted a higher register. And try not to be so harsh, he said - maybe something to do with our relationship. Like I'm a husband-beater." And she leapt at the chance to sing a song in the movie, scored by Burton regular Danny Elfman. "I love show tunes," Bonham Carter exclaims brightly. "I'm a gay man at heart."

Some have suggested that Burton's work has stopped being dark since the two became an item. Even Bonham Carter admits that, for all its gothic and macabre flourishes, Corpse Bride is rather an optimistic movie, where the dead seem to be having a good time. Does she feel guilty about this profound change? "I don't think I feel that guilty about it," she says. "I'd rather Tim was happy and other people were disappointed."

She explains that it wasn't until the end of filming Planet of the Apes that "ding! - and it was obvious" and they started dating. Friends were not surprised; it was only she who hadn't seen it. She felt "immediately comfortable and safe" with him, and, what was more, he was more than happy to move to London, claiming that Hampstead "was the only place in the world I feel at home in" after staying there during the making of Sleepy Hollow. "Years later, he came to live there with me. It seemed like serendipity," she says. "He loves the rain - the only person in England who likes the rain."

Her relationship and having a child has definitely put acting in second place, though she is due to appear in a TV production in November called The Magnificent Seven as the mother of seven autistic children. "I've had relationships before but this is family," she admits. "Acting has definitely become a satellite activity. It's not where I put my sense of self or self-esteem. I don't need it to feel real."

She likes her life now, she continues. "I don't need to reinvent myself or escape." And can we expect a return to costume drama any time soon? "Actually, I haven't done one since about 1998, and I wouldn't mind doing another." Time to dust down those parasols.

'Corpse Bride' is on nationwide release from Friday