Bob Hoskins - cuddly cockney, loveable rogue, 'testicle on legs' (thanks film critic Pauline Kael) and former face of British Telecom - is in a bit of a strop when we first meet on one of the cobbled streets around the back of King's Cross Station. He's suffering from hayfever for the first time in his life, he says. But still it's easy to butter up the old sod. Throw him a compliment and he's away. It works for the photographer ('I've been looking forward to this') and later it works for me when we sit down for a chat in a cafe around the corner from his house in Primrose Hill ('I like your new film').

We've lured Hoskins to King's Cross to photograph him looking moody in the streets behind the station - a setting chosen because it was also the seedy location for his excellent 1986 film Mona Lisa, in which he played a recently released con and minder to a high-class prostitute (played by Cathy Tyson). The scenes shot there show prostitutes lining the curbs as potential punters crawl by. Hoskins jokes that King's Cross was the only part of London with which the film's Irish director, Neil Jordan, was familiar.

But King's Cross also embodies the spirit of another of Hoskins' best films, The Long Good Friday, the 1979 gangster drama that Time Out readers have chosen as their favourite London movie. Hoskins plays Harold Shand, a savvy London criminal looking to inject a little criminality into the coming regeneration of the East End by inviting some crooked Americans to invest in the Docklands. 'Thatcher had just happened when we made the film, she'd just got into power,' Hoskins recalls. 'It was exactly her vision. That's why it was so frightening; a gangster spouting Thatcherism.'

As Shand, Hoskins was vicious and funny, unpleasant yet attractive; his character oozed charm and confidence, deploying both in deception, robbery and murder. Shand is also responsible for one of the most memorable moments in British cinema: the industrial freezer scene in which he hangs a series of adversaries upside down on meat hooks to persuade them to squeal. There's a sense of prophecy, too, within the swagger of the film's plot; not only does it predict the redevelopment of the docks, but it ties that regeneration into a coming Olympic Games (albeit in 1988). Bent copper, Parky (Dave King), throws Shand a striking - if unpalatable - question as they stroll along the river: 'Can you imagine nig-nogs doing the long jump along these quays?'

But, despite its later success at the box office, the makers of The Long Good Friday tried to bury the finished film. Its producers were unhappy with it and - according to Hoskins - tried to sabotage the movie by dubbing his character entirely in a Wolverhampton accent. 'They did it to fuck up the film, to destroy it,' Hoskins remembers. 'A Brummie accent didn't work. It had to be London. But they hadn't looked at my contract, which said they couldn't dub me. I saw about ten minutes of the film and stood up and said, "You're nicked sunshine, every one of you. I'm slapping an injunction on you." I got a lot of support: John Boorman, Alan Parker, even Warren Beatty called me and recommended a lawyer.'

Eventually Hoskins himself had a hand in persuading George Harrison's production outfit, Handmade, to buy the film. 'George joked that he wouldn't have done it if he'd known what it was really about,' Hoskins laughs. 'He was a pacifist.'

Hoskins has been in showbusiness since the late '60s - first theatre, then television and film - but the more we talk over a couple of coffees ('cappuccino please luv, a big one') the more obvious it becomes that he's lost none of the straight-talking attitude that he gained growing up in Finsbury Park during the Blitz. 'I spent the first three years of my life under a kitchen table, know what I mean? I drive through there now and wonder if it's changed; the colours of the faces have changed, but not really.' He left school at 15 and took a series of different jobs before entering the theatre at 25; the story (if it's to be believed - he tells a few anecdotes that you wonder might be porkies) runs that he accompanied a friend to an audition at the Unity Theatre and landed the lead role himself.

'I was a Covent Garden porter,' he explains, before rattling off a list. 'I was a window-cleaner; I was in the Norwegian merchant navy; I was a plumber; and I was a vacuum cleaner salesman; I had to do all sorts of things to persuade people to buy one. I used to hang them from people's ceilings. Showbusiness, mate, showbusiness.'

There's little about Hoskins' manner or language to suggest almost four decades at the heights of British television, theatre and film. He adopts a mocking thespy voice when using the word 'theatre'. He trades on how down to earth he is, whether recalling the famous occasion when Francis Ford Coppola called him up at home in the early 1980s to offer him a part in The Cotton Club and woke his newborn baby, Rosie ('I said, "Yeah, and this is fucking Henry VIII and you've just woken up my fucking daughter" '), or explaining how he hardly ever goes to the cinema these days ('I spend all fucking day making films, why watch them in my spare time?'). He's a chippy Londoner through and through: 'I know where I am in London. I know the procedure. Abroad is abroad, and I feel like a foreigner there.'

But he's still happy enough to pop across the Atlantic occasionally and return with a bundle of cash. Quality, it seems, isn't always so important; Hoskins has recently worked on Son of the Mask and Garfield 2, as well as better films such as last year's Vanity Fair and Stephen Frears's upcoming Mrs Henderson Presents.

'I've done my lead roles. I've reached the age of the cameo. You're only there for two weeks, they treat you like the crown jewels, you get paid a load of money, and - if the film's shit - nobody blames you. Wonderful. I'll have some of that. That'll do.'

His role in next month's Mrs Henderson Presents is a lot more substantial - and revealing. Not only is he the film's co-star alongside Judi Dench, but he even gives us a flash of full-frontal nudity. The film is the story of Soho's Windmill Theatre in the years before and during World War II. At its core is the relationship between Laura Henderson (Dench), its unlikely and widowed owner, and Vivian Van Damm (Hoskins), her manager. Together, Henderson and Van Damm developed a radical way of bypassing the obscenity laws by presenting nude actresses in tableau poses.

'The girls were totally tyrannical,' Hoskins says of the young actresses in the film. 'Their attitude was: we strip off for this film, what do you do? I had to strip off, just to get my authority back!'

No interview with Hoskins would be complete without mention of the 'It's good to talk' ads he made for British Telecom in the mid-'90s. His usual gag is to say that he made them for 500,000 reasons - each of them with the Queen's head on. 'I was building a new house and was in the hands of an architect and a builder and a fucking big building site. If I hadn't paid the bills, that's all I would have had - a big building site. I was up to my neck in shit and thought: That'll do, that'll do.'

That'll do. It's a phrase he uses a lot. It reeks of common sense, the law of the street. Like, who wouldn't do the same?

'I've got one big ambition left in my life,' he says. 'And that's to do a film where I can walk to work and come home for lunch. They're always making films over at Primrose Hill and I live just round the corner and I'm always shouting, "Why the fuck ain't I in this film?" '

That'll do, Bob. That'll do.