After seven years banged up on the small screen, the inmates and screws of HMP Larkhall are breaking out of G-Wing and into a new life on stage in Bad Girls The Musical at the West Yorkshire Playhouse.

Billed as a dangerous mix of deception, romance, riots and revenge, the stage show has been written by the creators of the television series, with book by Maureen Chadwick and Ann McManus and music and lyrics by Kath Gotts.

The musical story charts the battles of new, idealistic Wing Governor Helen Stewart against the entrenched old guard of corrupt Officer Jim Fenner and his right-hand woman Sylvia Bodybag' Hollamby. Romance develops between enigmatic lifer Nikki Wade and the Wing Governor, but a death on the wing forces the women to take sides and seek their own justice.

An invitation was extended by the Playhouse press office to interview the "intimidatingly beautiful" Hannah Waddingham. Never mind that she would be playing the lifer', Nikki Wade, how could York Twenty4Seven refuse?

Why is Nikki serving life, we ask gently. "She's one of only two lifers in there. She's inside for bottling to death a policeman who was raping her girlfriend. She bottled him in the neck," says Hannah. "I'm 5ft 11. Stick a bottle in the neck and that's going to shut up a man at 50 paces!

"Some would see her as a heroine, and that's where there's a meeting of minds with the wing governor, Helen Stewart. She realises Nikki is not only wrongly imprisoned but she should be released on appeal and have her name cleared."

For all the success of prison musical Chicago, the Bad Girls plot does not sound the most instantly musical of shows. "For my character to break into dance, I have to try to put the lighter side of Nikki to the fore," Hannah says.

"Kath Gotts needs the most praise for transferring the TV show to the stage. She's had such a long association with the show (she wrote the theme tune and incidental music for four series) and she's found a musical way of dealing with setting up the story. All of us have signature tunes to introduce ourselves.

"Mine is all in minor keys. I'm a mezzo soprano, we sing pop rock in this show, though I do have an operatic side too."

So far, you may be under the impression that Bad Girls could be somewhat grim, but think again. As with the TV series, drama with a punch will rub shoulders with heart-warming comedy with a punchline. "It's a marriage of the serious and the humorous, but it's also high camp, so it takes the mick out of itself, with the audience being told pretty early on that they can have a laugh and it's not all doom and gloom," says Hannah.

She distances the show from the Prisoner Cell Block H stage spin-off. "Prisoner Cell Block H was always camp by its very essence, whereas this is more hard-hitting and gritty, with some campery thrown in, and not the other way round. If it had been too camp I wouldn't have touched it with a bargepole. I wanted something that was gritty and realistic and then had something light brought into it."

Hannah has been involved in the gestation of Bad Girls since participating in workshops with Kath, Maurice and Ann in December, 2004, in London. "I saw the reaction to it in the workshops, where people maybe came in feeling cynical but were whipped up into a frenzy by the end. I don't think there's any doubt that it will transfer to the West End, and actually it's a shame I can't do it there, but I couldn't possibly turn down Eric Idle's Spamalot, which I'll be doing at the Palace from October," she says. "If I could have held on to this show I would, such is my feeling for it, and besides, I feel it's my role."

Nevertheless, she will switch to Eric Idle's Spamalot this autumn. "I'm going from militant lesbian in Bad Girls to a flouncing diva who comes up out of the stage in Spamalot.

"I got to see the show in America; the company kindly paid for my flight and the hotel and for tickets for my friends, and the songs are absolutely hysterical," says Hannah, who has received some better news still.

"Tim Curry is going to be my leading man; they're specially bringing him over and I'm so chuffed about that.

"I'm utterly overwhelmed to get the part, especially as there's only one principal female role."

First, however, Hannah must share the stage with a bunch of very Bad Girls.

Bad Girls, West Yorkshire Playhouse, Leeds, on the run until July 1. Box office: 0113 213 7700.