"What on earth are you doing?"

she demanded. "They're all going to think we're crazy."

"But mum, Helena Bonham Carter is playing you."

"Oh, in that case, fine."

He got the idea when he had to make a speech on his 50th birthday. "It suddenly dawned on me that the last big party I threw was my bar mitzvah and nobody turned up because it clashed with the 1966 World Cup final."

It didn't help either that his dad's life was collapsing around him. He suffered from an obsessive compulsive disorder that made him dither about things going wrong, meaning they usually did. The small convenience shop he ran with his brother was about to be wiped out by a giant supermarket across the street. The house catches fire. The life savings which he kept in a cardboard shoe box because he didn't trust banks go up in smoke. Weiland's mother was so busy worrying about his dad that she'd no time for him.

"She dedicated her life to this man who wasn't terribly well. You did in those days. You made your bed, you lay in it. She came from a family of eight at a time when people were still dying of diphtheria and living in a two-bedroom flat.

As a child I was incredibly needy of attention. Nothing has really changed, I have to say. It's one of those things I have not been able to throw off, which is probably why I became a film director and at this particular stage of my life I'm making this movie."

Sixty Six could easily have been filmed as a tragic story. But Weiland is no Bergman. He's made a lot of commercials. He did the Hollywood thing with City Slickers 2.

He directed Rowan Atkinson in Blackadder Back & Forth. Comedy comes more naturally to him. His best friend Richard Curtis helped him write the original treatment and then polished the final draft.

"There are a few of his touches in it, but he said this is yours, it can't be mine." So gloomy it's not.

"I saw humour in rejection, " he says. "My dad wasn't really much of a dad. He never really took me anywhere. I was a child who was invisible to his parents. Things were never quite right, they didn't go the way they should. My childhood was a succession of ironic disasters."

Sixty Six catches this ruefulness beautifully. It's a rite-of-passage movie that takes the pain out of growing up. "Dad is gone now, " says Weiland. "The movie gives me an opportunity to fix him on the screen. I couldn't really do that in real life because he was too far gone. I was a great sadness and a great frustration. I couldn't really get him out of where he was, the place that he was trapped in. I suppose the movie was a slightly cathartic thing. I don't think he comes out of it badly. Eddie Marsden plays him so well that you really sympathise with this man. You know he's a man in trouble, a man caught up in a world he doesn't quite get."

Many of the props used in the movie belonged in Weiland's childhood home. "My mother hoarded everything, " he says. "When it came to dressing the movie I had so many actual things from my past. We use the same carpet. The real front-door bell. Even the duster coat my dad wears in the shot. She even had kept the Terry towels. Again it was an illness. I'm completely different. Everything in my life changes . . . except my wife. I don't keep anything."

His mother met with Helena Bonham Carter. "They got on very well. Helena has a remarkable resemblance to my mother as a young woman." To play his younger self, Weiland picked Gregg Sulkin, a 13-year-old Jewish boy who had never acted before.

"He didn't want to be an actor, " says Weiland. "He came to the audition just because his cousin did. From working with so many children in commercials I have an instinct for knowing who can do it and who can't. Gregg was very good at feeling sorry for himself, even though, unlike me, he had no reason in his life to feel sorry for himself." When Gregg was eight he was scouted to play football for Queens Park Rangers, along with his friend Dean Parry, who has since played for England Under16s. After four years with QPR, he did two years with West Ham and is now, at 14, playing for Tottenham. "I'm a right-back, " he tells me later. "I'd like to emulate Gary Neville who plays quite aggressively and passes the ball well. He's a complete player. Obviously a right-back doesn't have the influence in the game that a centremidfield player does, but he's a person I look up to."

He doesn't know whether he'll end up a footballer or an actor.

"My mother would prefer if I became a top tennis player, " he says. "But right now I just need to concentrate on school."

With Sixty Six about to come out on Friday, Weiland feels a certain apprehension. "Right now I'm not in a good place, " he says. "I feel that now I'm up there being judged like I was when I was a child." On Sunday, Helena Bonham Carter's two-year-old son broke an arm, which meant she wasn't able to do any publicity. The massively hyped comedy Borat is opening on the same day. "It's as if my Bar Mitzvah is repeating itself. Will anyone come to my second Bar Mitzvah. I'm someone who has sold products all my life. I see Sixty Six as a product. I want it to sell.

It's a story I wanted to tell but I wanted to tell it to other people."