Wanna be in my gang?

They say that if you remember the Sixties, then you weren't there - and in a funny sort of way this is true of author Jake Arnott. Born in 1961 - and therefore only eight at the decade's close - Arnott's debut novel, The Long Firm, created one of the most persuasive accounts of the Soho underworld of the 1960s. In this now almost mythical era, gangsters rubbed shoulders with pop stars and politicians, while Swinging London's society photographer, David Bailey, immortalised the Kray twins alongside Mick Jagger and The Beatles.

They say that if you remember the Sixties, then you weren't there - and in a funny sort of way this is true of author Jake Arnott. Born in 1961 - and therefore only eight at the decade's close - Arnott's debut novel, The Long Firm, created one of the most persuasive accounts of the Soho underworld of the 1960s. In this now almost mythical era, gangsters rubbed shoulders with pop stars and politicians, while Swinging London's society photographer, David Bailey, immortalised the Kray twins alongside Mick Jagger and The Beatles.

Arnott's The Long Firm is full of fictional composites from the time. The pivotal character, Harry Starks, is a Jewish East End gangster who happens to be gay (like Ronnie Kray) and given to torturing his victims, as did Charlie Richardson. Those entering Starks's orbit include Lord Teddy Thursby, a homosexual peer along the lines of Lord Boothby; a former Rank starlet fallen on seedier times (partly based on Diana Dors and partly on former starlets too libellously alive to mention); and a trendy sociologist with touches of Professor Laurie Taylor, Malcolm Bradbury's supposed inspiration for The History Man.

Arnott cheekily sprinkles this fictionalised cast with real people such as the flamboyant MP Tom Driberg; the gay record producer Joe Meek; a broken-down Judy Garland; and the gangland figure Jack "The Hat" McVitie - later murdered by the Krays. It all adds to The Long Firm's lustre of authenticity. The book's unique selling point, however, is not its cast of the real and semi-real, but its casual assumption that a high proportion of this hip and happening demi-monde was gay.

"One of my inspirations was the death of Ronnie Kray," says Arnott. "I rather hoped that someone would come out with the story about the private life of a homosexual gang boss. There's so much nonsense that has been written about the Kray twins, but all the interesting things always seem to be ignored."

The private life of a homosexual gang boss as depicted in The Long Firm includes orgies, "house boys", bouts of depression and a good deal of persuasion with a white-hot poker. Not that Harry Starks is in any way a one-dimensional cockney hard-man. He's also a believer in the Empire (he relaxes to LPs of Winston Churchill's wartime speeches) and the capitalist order.

"Ronnie Kray was obsessed with the great Empire men - a lot of whom were themselves not of a conventional sexuality," says Arnott. "Another big influence on me is Bertolt Brecht, who used the figure of a gangster in order examine capitalism with its gloves off. One of the most abiding myths about the criminal underworld is that these people are somehow anti-Establishment. I think the exact reverse is true."

Having snapped up the film rights before the book was even published in 1999, the BBC has at last made a four-part dramatisation of The Long Firm. Closely adapted from the book by Joe Penhall, author of the award-winning National Theatre play Blue/Orange, the Ronnie Kray-like Harry Starks is played by Mark Strong - Tosker in Our Friends in the North.

"I didn't really want somebody who had a lot of gangster baggage," says one of the programme's producers, Liza Marshall. "I mean, we could have gone down the Ray Winstone route..."

The producers also needed someone of the calibre of Mark Strong (who, apart from Our Friends in the North, has a distinguished theatre career) because Harry Starks remains a slightly mysterious character in the book. He's always seen from other people's points of view and doesn't have his own voice in the narrative.

"I don't think he's ever physically described, except as being brutish," says Strong, whose Starks is physically more brooding Al Pacino in Scarface, than explosive Bob Hoskins in The Long Good Friday. "It was felt he had to appeal to men and women, with a certain amount of charisma and charm. You had to imagine why someone would fall under his spell.

"As for his homosexuality, the way to play him was as a dead straight, well turned-out London guy with no campness whatsoever. The only thing I did was if we were in the street, I'd look at boys instead of girls."

Near faultless casting includes a sly performance from Derek Jacobi as Lord Teddy Thursby; the criminally under-used George Costigan as the bent vice-copper, DS Mooney; Lena Headey as the ageing starlet Ruby Ryder and Shaun Dingwall as Lenny, the Seventies sociologist. One name you won't see on the cast list, however, is that of a pop star.

"It's extraordinary how often we're expected to watch pop stars play gangsters or villains," says Arnott. "Roger Daltrey as John McVicar, Phil Collins as Buster Edwards, the Kemp boys from Spandau Ballet as the Krays twins, Matt Goss as Charlie Richardson..."

Indeed, the conflation of London gangster and pop star goes back as far as Nic Roeg and Donald Cammell's 1970 film Performance, in which a fugitive cockney gangster, played by James Fox, holes up in a rock-star mansion inhabited by Mick Jagger and Anita Pallenberg.

" Performance is quite a good reflection of the Sixties itself," says Arnott. "There's so much vigour and energy in the film, and it ends up in a bit of a hippie mess - very much how the decade was. But I'm not very interested in metaphysical speculation; I wanted to look very much at real social and political aspects."

Arnott is a bigger fan of The Long Good Friday, in which Bob Hoskins's old-school London gangster finds himself falling behind the times as he tries to interest the American mafia into buying a sizeable slice of London's Docklands. "One of the most prescient British movies ever made," says Arnott. "It was made in 1979 and it almost completely anticipated the Eighties. It's a very Brechtian look at that world. The huge irony is that at the end, the mafia say to poor old Harry, 'Sorry, we don't deal with gangsters'. They've cleaned up their act far more than he has."

Peter Medak's 1990 film The Krays was a wasted opportunity, thinks Arnott, with Gary and Martin Kemp as Ronnie and Reggie ("they could have done with a couple of feet around the waistline"). But then the Krays were still alive when the film was made - a potent presence even while rotting behind bars.

"Philip Ridley's script was based on the Greek myth of Castor and Pollux, the twins born when Leda and the swan coupled. Apparently, at the beginning of the film, a swan flies over, or something..."

Arnott leaves his deepest derision however, for a film that opened in the year just before The Long Firm was first published - Guy Ritchie's Lock, Stock and Two Smoking Barrels. "It's the worst genre of all - it's a feel-good gangster movie", he says. "Absolutely nothing to say about anything at all - it's like one long beer commercial. The trouble with a lot of these British gangster movies is that their makers talk to these guys and they believe every word they say. And people do get drawn into this world. There are a lot of gangster groupies. I very consciously wanted to avoid that."

Arnott had his own experience of the celebrity ex-villain phenomenon at the book launch of The Long Firm. "Freddie Foreman came up to me - he turned up with Barbra Windsor, in fact. It was like a scene from one of my books. He said, 'I want a word', and I thought, 'Oh, no'. It turned out that what he wanted was to talk about his book deal and about his film proposal. He was networking. You'll meet these retired villains at book launches now, and they're all trying to work the room."

But while the old crooks are still knocking about, their haunts are long gone. The BBC2 adaptation of The Long Firm managed to snatch a few exterior shots of Soho, but the new media-friendly and (ironically, in the context) gay-friendly village has changed hugely since its shabby Sixties self.

"We mocked up some streets in Hoxton - the only area where you can go and the buildings are the same height," says the producer Liza Marshall. "If you look at old pictures of Soho, it's pretty much all prostitutes and the odd coffee bar."

The look of the series is surprisingly washed out, with none of the razzmatazz one might associate with the Swinging Sixties. The soundtrack also eschews any of the obvious songs of the period.

"I hate that wallpaper of really famous Sixties songs that becomes like a pop video," says Marshall. "Hopefully, the songs we have chosen are a little bit more surprising. I've been working with Universal, and they've opened up their back catalogue at Decca. Hopefully, what we've chosen will be stuff that people have heard of, but surprising none the less.

"It was a very conscious decision not to make the film fetishistically period. I really wanted it so that you felt in amongst the characters and their world, and I don't think those types of people would have had trendy Sixties furniture all over the shop. I wanted to make it feel real."

'The Long Firm' is on BBC2 on Wednesdays (starting tonight at 9pm)