From the start, it was strange party. To begin with, the guests eye each other with mild suspicion and an expectant air. The talk was of fashion and films. The champagne was modest and growing warm under the studio lights. Who was there? Two ELLE fashion editors, one photographer, one journalist, one publicist, one six foot model and a five-foot film star. In front of a large mirror, the star was being talked into a collection of designer menswear to shame the most avid admirer of labels.

Throwing a pose in a Yohji Yamamoto coat, fingering the fabric of a Comme des Garçons jacket, frowning comically under a black Homburg before pulling it off with a sharp, 'Jesus! Would you buy a used car from this man!', he called for more drink and stripped down again to his little socks and Jockey briefs. The ladies turned their faces away.

Bob Hoskins is not like most film stars, but he still likes dressing up. When we explained to his agent that we wanted to use him as a model, she recommended that we go straight for Yohji. He was, she said, hot on Japanese designers. Hoskins says that with a body like his you can't be too picky -as long as it doesn't make him look like 'a bleedin' rabbi' (Paul Smith coat, £145) or a 'bowling skittle' (Yohji jacket, £415).

Hoskins has style; he knows what clothes can do for a man. So does Neil Jordan, director of his forthcoming film, the Cannes-dominating Mona Lisa. Perhaps Palace Pictures' best to date, the film is about many things- the friendship between a high-earning, black call-girl, Simone (Cathy Tyson), and her endearingly naive minder George (Hoskins); the problems a normal bloke has earning a dishonest crust; the brutalised businesses of prostitution, prejudice and heroin. In its hero's off-screen opinion, it's the story of the 'seedy London underworld seen through the eyes of an Irish poet'.

It's also a film about clothes. The ostentatious finery of Simone's wardrobe signals the end of her clip-joint career; and George, who leaves prison in a brown leatherette bomber jacket, flares and a floral shirt, has to learn from her the true lesson of style: how to make it lie for you. George's clothes are magical agents of transformation, paid for in wads of greasy twenties. To escort his charge around the lucrative lobbies of West End hotels, he must be dressed in Savile Row suits and cashmere overcoats; a smart, sharp look that Hoskins pushes from sweet ingenuousness to edgy menace with just a flicker of the most expressive nostrils on screen today.

Hoskins is not an easy man to dress. He's too short, too round and as solid as a British bulldog. But nice girls still love him and the looks that put him top of any list of unlikely sex symbols. Even if the Yohji designs we styled him in fitted where they were meant to hang loose, even if all the trousers had to be turned up on the spot, he still looks as people like to imagine he is.

The London cabbies' favourite fare is supposed to be a bit of rough with a tongue of silver and a heart of gold, the sort of chancer who dresses in East End schmatter to clinch a dodgy deal and win the tart with social ambition, the bloke who smoothes down his pockets in high street windows and says 'You're all right, my son'.

The real Hoskins is not as wide as the Old Kent Road. He is a fine actor who has played Arthur Parker in Dennis Potter's Pennies from Heaven, Iago in Jonathan Miller's Othello, and writer Stanley Gould in the new Alan Alda film, Sweet Liberty (due for release early September). Understandably, he is tired of the assumption that he can only do gangsters ('please don't ask him that one,' hisses the public relations lady).

He is, of course, working class, north London-raised and firmly fixed in the public's affection as a kind-hearted hero of the people. And true to the form, he knows what he likes. He likes the Cerruti trousers made specially for him in Mona Lisa. He likes braces and sent out from the studio for a pair. When they arrived, they were wrong ('I meant proper London braces with the metal bits, not this Ascot crap'). He likes the blue and white striped Paul Smith shirt.

He also likes being cuddled and kissed by model Jeny Howorth, twice his size and half his age.

For the camera, they got to know each other quicker than the most precocious campus daters. She, a good foot taller in her high, suede Manolo Blahniks, played out the comedy of an average male fantasy, grabbing him round the neck, putting her chin on his head, her knees round his neck, her nose in unmentionable places. He pulled her Romeo Gigli evening dress down off her shoulders, suddenly stopped and turned to the photographer: 'What sort of bloody magazine is this for, anyway, Tel?'

Together they posed and pouted, snuggled and romped. Hoskins imagined the scene - 'You see, Jeny's my girlfriend and we're going up to town for a posh dinner and I've made a real effort to look smart. But she doesn't think I'll do, so she's giving me a hard time.'

When Hoskins thinks about clothes - not a lot, as it goes - it's not far from this scenario. 'I never used to think about them at all,' he says, 'until I met my wife Linda and started noticing how she dressed. Well, you have to look a bit tasty when you're out with the old lady, don't you, for her sake? I'll get a suit made in Savile Row occasionally, and I like some of this stuff I've been wearing today. Any chance of a discount?'

What he would much rather talk about is the film that won him Best Actor award at this year's Cannes Festival; how the news of his success came from France while he was weeding the garden and how he had to get from London to the presentation in four hours; how he rates Neil Jordan (highly); how he plans to make a directorial debut with a film based on an old gypsy legend and how he wants a set of our pictures to show his wife.

Mrs. Hoskins - mother of Rosa, three, and baby Jack - shouldn't take them too seriously. Asked what could be better than champagne, fabulous clothes and a beautiful girl for an afternoon, her husband replies: 'I could be at home with my missus having a cup of tea. This fashion stuff is nonsense.' And he means it. Like George, the character created specially for him, Bob Hoskins wears his heart on his sleeve. He won't admit to caring much who designed it.