The Spud we like sprouts big

Pearl Harbor is the most expensive Hollywood movie ever given the green light. At $135 million (£90 million), it beats Waterworld (before shooting started), Star Wars and Titanic in terms of committed budget. It's directed by Michael "Armageddon" Bay and stars Ben Affleck, Kate Beckinsale and the 29-year-old Bremner. He's so clearly delighted about this, so pleased and excited, he squirms in his squeaky leather chair when I bring it up.

"I don't know a lot about it yet," he says. "I play Ben Affleck's co-pilot. It's a good, decent part, running throughout the movie." Where will it shoot, I ask, since Affleck - despite being American - plays a member of the RAF? Bremner grins his head off. "Hawaii, Mexico, Texas, LA and, I presume, here."

He intends to take his London-born partner and his eight-month-old daughter with him. That's the beauty of being an actor, he says: you get to see your child much more than the average office plod, working nine-to-five.

But before the glamour of Pearl Harbor, Bremner is appearing in a Channel 4 series which couldn't be more different. The Secret Life of Michael Fry is set in Wales, and tells the story of a local planning officer's bizarre, unwitting involvement in an internet porn scam. Bremner plays Fry, a normal bloke who's been left holding his baby, and the romantic lead. On the day I visited the set, several women in leather thongs were doing unspeakable things to men dressed in nappies and Bremner was sitting around in an uncomfortable suit and tie.

The Secret Life is written by Paul Abbott, best known for Cracker. It's stylishly shot, bleakly humorous and makes the most of Bremner's natural soft-heartedness - you can't imagine him playing a thug; it wouldn't come easily. "I hadn't a clue who Paul Abbott was before I did this," he says, honestly, "but the script was brilliant. I love that Michael Fry's sooo normal. It's a good distance from all the whackedout stuff I've been doing of late."

Bremner started acting because his parents got fed up dragging him around an Edinburgh supermarket on a Saturday morning. "Me and my little sister'd be kicking and screaming, so they found this cr?che where they could dump us. It happened to be situated in a community theatre building, which also ran youth theatre." When he got too old for the playgroup, he joined the theatre.

"I don't remember the productions too well, just the crack of it. I really enjoyed the company of those people." Most of them were female. In one production of Caryl Churchill's Top Girls, Bremner played a 12-year-old girl who was having her first period. "The thing is," he says, laughing, "I played it seriously. It was a serious, all-female production that just happened to have me in it."

Still at school, he got an agent and - amazingly, considering his lack of proper training - began to get work almost immediately. He was in several films as a teen-actor, played Archie in Mike Leigh's Naked ("that opened a lot of doors") and came down to London in a Traverse theatre production which transferred to the Royal Court.

And then came Trainspotting. It was a play before a film, of course (and the Irvine Welsh book before either). In the stage version, first in Scotland and then at the Bush in London, Bremner played Renton, the lead. So was he disappointed not to get the same role in the movie? I'm not prepared for the frankness of the reply.

"Yes. I thought f***! Immediately I was. I read the script and it hadn't occurred to me that they wouldn't see me for the part and then suddenly I thought: oh my God, this is written for Ewan McGregor! It was in the writing. It was always written for him, from the outset. So then they said to me: we're thinking of you for the part of Spud. And I thought: I'm not going to do it."

Did you throw a tantrum? "No-oo. I was just disappointed that I wouldn't even be asked to audition for Renton, cos the stage play had been so successful. I got over it. I needed to earn some money, so I did it - and nobody could have known how big a deal it would be."

Everyone involved in Trainspotting benefited, he says; it captured the Zeitgeist at the very beginning of the ghastly Cool Britannia nonsense, and it slotted perfectly into a cultural movement which seemed to value the gritty and streetwise above the slick and Merchant Ivory.

Bremner is on "good terms" with the cast and crew of Trainspotting, though the only person he still sees is Kelly MacDonald who played schoolgirl Diane. Now that he's a dad, he doesn't socialise too much and he's never been a big theatre or filmgoer. I ask him, all the same, whether he hankers after the stage, since this seems to be the fashionable attitude nowadays for any actor, whatever age.

"No," he says, almost leaping out of his chair. "I mean, it all depends on the merits of the production, but I don't believe any big film actor who says their heart lies in the theatre. What a lot of s**t. I don't buy it."

Refreshing, huh? Later, he says: "Acting is such an ephemeral business. It's very foolish to take it that seriously." What on earth will Hollywood make of him?