Walking into the dining room of the Halcyon Hotel in London on a Sunday afternoon made me realise that not only is there a God, but that He is very kind indeed. It is not often that you get to spend time with a handsome and glamorous young actor, but to have three of them, together, at once, is rather like settling down with a family-size box of chocolates; a thrilling yet rather daunting prospect. But there they were, in a sweet, neat row, Rufus Sewell, Tom Hollander and Joseph Fiennes, all smiling and all very, very pretty.

To followers of tabloid gossip, Rufus's Adonis-type looks are the stuff of legend - a totally untrue legend - but a "saying no to the sexual advance of Madonna" legend nonetheless. (In the autumn of 1995, when he was appearing in The Rat in the Skull at the Royal Court, she apparently asked him out on a date and he refused. In fact, they had a drink together at the Ivy before he had to go to the theatre.) His name also been linked with Kate Winslet, Patsy Kensit and Emma Thompson; he denies the rumours with the boredom of someone telling the truth. Anyway, in the flesh, he does not disappoint. The dark curls, green eyes and angular face could launch a thousand teen bras. Dressed entirely in Prada (which he confesses to have borrowed and not given back), he cuts a glamorous swathe.

Joe has all the expected well-chiselled attractiveness of his elder brother, Ralph, with a face of classic proportions. But Joe's eyes are brown, with those long, thick, girlie eyelashes that separate into pretty little clumps when wet. He is dressed down in combat trousers, comfy walking shoes, and the sort of thigh-length leather car coat only ever sported by flashers or actors. Despite his scruffiness, he is introduce-to-mother material.

But it is Tom who is the surprise. All blond and baby blue-eyed, he is neatly turned out in a tweedy green "op-shop" suit. No taller than 5ft 5in, he is charm itself. With a veneer of common sense, born I suspect from every woman's desire to look after him, he radiates good-natured wit.

Sewell, Fiennes and Hollander are all starring in the new low-budget Brit Flick romantic comedy, Martha - Meet Frank, Daniel and Laurence. It is the story of three best friends who, during the course of a long weekend, all fall in love with the same girl, Martha (Monica Potter), who has left Minneapolis for a new life in London. It looks set to be the comic hit of the season, and will make this spring's hottest young bucks on the block.

The delicious thing about this meeting though is that, devoid of the usual actorly arrogance and pretension, none of them really seems to realise this yet. As I sit down I get the feeling that rather than being patronised, I'm about to play teacher to a playground full of boisterous boys. It's not going to be easy. Rufus and Tom are too busy showing off, each trying to outbanter the other, to pay much attention to my probings, and Joe, well, Joe just sits and blinks myopically from his corner pew.

"So," I start out gently, "did you all get on?" "They sit to attention. "Mmm, yes, yes we did... I know I said that boringly quickly, but we did, we did, we did," says Rufus, attacking my cigarettes with the gusto of a child at the pick'n'mix counter. "Well, look at us, have you ever seen three people more friendly with each other?" adds Tom, leaning back flamboyantly on the banquette. Joe just smiles. "So, no bully-boy fighting then?" I delve. "No... we're all pathetic, we're all cowards," Tom assures me.

"We did bond... but not that much together... thanks," quips Joe. The other two look at him, slightly stunned that he actually spoke. There is a pause. "No... the fight in the film was brilliant fun," announces Rufus, taking over. "We could all show off our crap fighting skills. Kicking people in the shins whilst pointing behind them and stamping on their feet." Rufus rocks with laughter.

In the film Tom is Daniel, a glamorous music biz character, with money and a fashion-magazine lifestyle; Rufus is Frank, a drinking, smoking, swearing out-of-work actor who was once famous and is now jealous of his friend, Daniel. And Joe plays lovely, gentle Laurence, the sensitive soul who teaches bridge to middle-aged ladies and is caught between the two bickering friends.

Did they each get the part they wanted? "No, I wanted to play Frank," says Tom. "I wanted to play Frank too," says Joe from behind his hands. "We all wanted to play Frank because Frank's a sad actor and so are we," says Tom. Rufus giggles and smokes ostentatiously, quietly pleased he had the part the other two wanted. "So Rufus," I probe, "prone to drinking whisky on a park bench, like Frank?" "Er, yes," he laughs. "I've done it and so has anyone who's ever been despondent or unemployed or bitter at any stage." Rufus once suffered the ignominy of having even his road-sweeping skills rejected - by Hounslow Council.

I turn swiftly to Joe. "Are you prone, like Laurence, to hanging out with rich old ladies whilst sporting a prep-school haircut?" Joe recoils from my question with the expression of a child caught stealing from the biscuit tin. "Um, what? Hum, busted. How did you know about that?" he jokes. "Um. No. In a word," he says, tweaking the end of the Bardy beard he has grown for the Tom Stoppard-scripted Shakespeare in Love, which he is now making with Gwyneth Paltrow.

"So, real acting was required then? I ask. "It required an intensive collective of resources to enter into that world... Oh God, what am I talking about?" He is flustered. "But you were very good at sensitively smouldering? I expand, trying to help. "Um, no... what was the question again?" I'm so sorry." He leans forward, trying to concentrate. I repeat: "Sensitively smouldering?" "Am I? I don't... do I?" He stares up from the table. "Don't flutter those eyelashes at me," I chide. "Oh? Am I doing it now?" says Joe.

Tom starts to laugh. "So are you good at rolling around sexually unsated on your bed, as Daniel does for hours in the film?" I inquire. "Oh yes," he announces to the dining room. "Always sexually unsated. Very much so. All the time. Actually, that was all spontaneous. It wasn't even in the script. We just thought that we'd do it. When we got the rushes back there were all these bits of me in bed and I was lampooned. Now it turns out that it's a very cherished moment in the film." He laughs.

"I particularly like your pants," I say. "Pants," he replies. "Weren't they nice boxers?" "No", interrupts Rufus. "They were clingy Marks & Spencer's." Tom laughs. "They bought me three alternatives and I chose the ones that were the most flattering." "Oh, yes. The ones with the padding... murmurs Rufus.

For the producer, Grainne Marmion, and the director, Nick Hamm, to have put these three boys together shows a remarkable amount of cunning. While none is yet at the film-carrying stage, as a boy band ensemble they complement each other beautifully.

"You cast actors who a) you want to work with, and b) you think are incredible to watch on screen," explains Hamm, whose previous credits include ITV's Dancing Queen with Helena Bonham Carter, and The Crucible for the RSC. "What I really concentrated on was finding three English guys who were fresh and coming through. I really think in these three you've got the next wave of movie stars."

Twickenham-raised Rufus, 31, is the most well-known. He marched on to our small screens in a frilly shirt in Middlemarch, then went on to smoulder his way through Cold Comfort Farm and The Woodlanders. Rufus, who has lived with his girlfriend Yasmin in Kentish Town, north London, for two years, trained at Central School of Speech and Drama. His childhood was bo-ho but impoverished. His mother delivered vegetables to support the family after the death of his father, an Australian animator who worked on Yellow Submarine and Roobarb and Custard. A naughty boy who once bleached his hair blond and painted his fingernails black, he brings a raw energy and natural good humour to the film.

Tom, at 30, is one of our most promising theatrical talents, who likes to walk the dog with his girlfriend and escape out of London at the weekends. Now appearing on Broadway with Liam Neeson in The Judas Kiss, he is an Almeida regular, starring, for instance, in The Government Inspector in 1997. He also played Saffie's boyfriend in Absolutely Fabulous.

A public school boy and former chorister in Oxford, at Cambridge he was a contemporary of the director Sam Mendes. When he didn't get into drama school - he says he was "too cocky" - he renewed his relationship with Mendes at the Donmar Warehouse to play Macheath in Brecht's Threepenny Opera. It is his sharp intelligence that prevents Daniel from turning into a loathsome character.

Then there is Joe, who at 27, is seven years younger than Ralph. He shares his brother's wafty hooray gypsy upbringing, having lived in 14 houses in almost as many years. After leaving the Guildhall Drama School, he went straight into the theatre, working almost entirely with the RSC, commuting up and down from Stratford upon Avon at weekends. He and Sara Griffiths, his actress girlfriend of seven years, clubbed together to pay rent both in Warwickshire and in south London. Now, having rarely graced the silver screen - he was the decadent Christopher in Bertolucci's Stealing Beauty - he has Martha and two other films on the go: Shakespeare in Love and the controversial Elizabeth, with Cate Blanchett. Joe has an enigmatic star quality which makes many think that he will soon eclipse his brother.

"So, Joe," I venture. "With all these films coming out you're about to be stupidly famous. Are you ready?" "Am I?" says Joe, blinking away. "Oh no, I'm stumped again... I'm really crap at this... aren't I? I suppose that's part and parcel of these interview things isn't it?" he says. "Are you nervous?" I ask. "Oh, yes I am," says Joe. "Actually, no I'm not, I'm just inept. Inept at talking about things."

They all sit back and relax. "So," I ask, "have you all seen each other since filming?" "Oh, we spent New Year's Eve together at Rufus's house and played Trivial Pursuit," says Tom. "Did you?" asks Joe, sounding surprised. "Yeah, where were you?" asks Tom. "I was in Costa Rica," explains Joe, trying not to sound glamorous.

"So you two obviously get on better than with Joe?" I joke. "Well, obviously," says Joe, playing hurt. "We're loud-mouth," says Tom."He's just sensitive." "Oh no, don't say sensitive," says Joe.

"Right," I say, trying to bring them to order. "Does Martha make the right choice at the end?" "Of course she does," says Joe, grinning. "D'you know?" says Rufus, "the driver who came to pick us up during rehearsals looked us all up and down and then came over to me and said, 'Well it's pretty obvious who gets the girl then.' I said 'what d'you mean?' 'Well, it's easy,' he says, 'it's not you or Tom, it's the other one. The good-looking fella'." Rufus combusts with laughter. "No," says Tom, leaning forward in mock shock. "The bastard."

I am inclined to agree. To be given such a choice is a nightmare indeed. No wonder Martha took a whole film to make up her mind. After my encounter I could hardly bring myself to decide. I did however, come away with a favourite... but that would be telling.