FEW creators of British crime comedies can claim to be drawing on their own experiences of life on the wrong side of the law. As writer and star of 'Orrible, however Johnny Vaughan isn't conning anyone. The comedy-drama, centred on a small-time London crook's attempts to fantasise himself into a role as a crimelord's right-hand man, is, says Vaughan, ''based on the great liars I have met and the great liars I have been. It's about the modern obsession we all have with being slightly villainous. They're people I've met in the pub, at football, but especially in prison.''

Vaughan served 25 months in Brixton and Leicester jails after buying cocaine from a police informer in 1988 at an M1 service station. He says the view from the top bunk gave him a new perspective on life. ''It sounds obvious, but if you have your liberty taken away, you put a greater value on freedom. Afterwards I wasn't so cynical and I wasn't so frightened to take a chance.

''It's like a general on top of a hill overlooking a battlefield. You can see where you are

going wrong.''

Inside, he devoured Russian classics, tuned in to Radio 4,

and started writing. His Christmas pantomime - Snow White and the Seven Cons - was granted an extended run by the prison governor.

Before jail, Vaughan had drifted through a series of McJobs: grill chef, jewel courier, boxer-shorts importer - but he was already used to financial ups and downs. The son of an engineering company owner, he had moved with his family from a modest home and state school in Totteridge to a big Victorian house - ''I can't remember how many rooms it had'' - in Leicestershire. He enrolled at Uppingham, the school Stephen Fry ran away from, while his older sister was a classmate of Lady Di.

But when Vaughan was 15, the family business crashed and they moved to ''a tiny, damp, horrid cottage in the middle of a field''. His parents divorced a year later, and instead of going to university as planned Vaughan headed for London - dreaming of becoming a writer - and jail.

When he was released in 1991, aged 24, he struggled to find work and presented corporate videos punting crisps, insurance, cars, lager, ''anything'', until a friend put him in touch with Rapido Television, who needed a host for a new cinema show. It was never commissioned, but the producers of MovieWatch saw his tape and offered him a job.

Vaughan, who says the worst part of being sent to jail was disappointing his parents,

didn't tell his dad he had the job until they watched the show together. ''I'll never forget the look on his face,'' says Vaughan. ''It was great to see the old boy so excited.''

He joined The Big Breakfast in 1997, quickly moving from sports to the host's beanbag, and with Denise van Outen dragged the show out of the doldrums. At the height of the show's popularity, Vaughan converted to Catholicism and married costume designer Antonia Davies. They have a 14-month-old daughter, Tabitha.

Presenting was, says Vaughan, a route into showbiz for someone who has no particular talent, and he quit The Big Breakfast after taking stock of his career. ''I suddenly thought: 'where do you go in British TV?' I don't want to be wearing a wig and going 'higher than a two, you say?' I've got to create my own stuff. 'Orrible marks me making a niche.''

As well as writing (with Ed Allen, son of Dave) and filming 'Orrible, Vaughan has signed a deal with the BBC, reportedly worth (pounds) 2m to (pounds) 5m, and is preparing a three-nights-a-week chat show for the new year. And his experiences behind bars should give him another big break with The Charity Committee. Also co-written with Allen, it's set in an open prison.

A real insider's guide.

Johnny Vaughan stars in 'Orrible on BBC2 at 9.30pm.