"My only proviso in doing the show was that I didn't have to wear fishnets and a bloody basque," says John Stalker.

Perhaps the best-known ex-policeman in Britain, John is talking about his role as the narrator in the 30th anniversary tour of the biggest, baddest and most orgasmic rock'n'roll musical of all time, the Rocky Horror Show.

Now 63, John came to prominence when, as Deputy Chief Constable of Greater Manchester, he was controversially removed from an investigation into the alleged "shoot-to-kill" policy in Northern Ireland.

Charges against John were dropped and his suspension lifted but he retired shortly after returning to the force.

Now a successful journalist, his book about the murders in Northern Ireland has sold 400,000 copies.

It's the bizzare juxtaposition of the establishment against the hedonistic nature of Rocky Horror that makes John's casting so inspired.

A crazy spoof on tacky horror films from the Fifties and Sixties, the show was made into a film with Tim Curry, Susan Sarandon and Meatloaf in 1975.

John hadn't even heard of the show when asked to take part.

"I still haven't seen the film or a show apart from the one I'm in.

"But I asked some friends who work in showbusiness what they thought and they told me that I'd enjoy it, so I said yes."

Traditionally, audiences kit themselves out in imitation of their favourite crazily-costumed Rocky Horror characters. As the narrator, John needn't have worried about having to dress up anyway.

There have only been a few narrators in the history of the show who've worn anything more outrageous than a dinner jacket, which, as John sees it, works best for the show.

"I see my job as bringing some sense of order to what is bloody mayhem really," he says. It just wouldn't work if I looked like one of the cast.

"You've got to have a certain sense of authority or the audience would crucify you."

Audience participation is vital to the show, with insults traded back and forth between them and the cast.

Along with Frank N Furter, who is played by Jonathan Wilkes, the narrator comes in for the most stick.

"The audience can be very well-accustomed to the show and know it even better than the cast.

"The audience's aim is to get one over on me but I just insult them back and they love it.

"It can be a lonely place out there. But having said that, it's a lot less lonely than standing in a witness box during a murder trial and I've done that many times."

Lonely or not, John hasn't been put off the show.

Originally cast to peform for four weeks, his run has now been extended.

"I really enjoy working with with the cast. Jonathan Wilkes is only 24 and the average age of the company is 20s.

"They're so energetic, so ambitious. You get to my time of life and see a lot of cynicism but they've got the sparkle of stars in their eyes.

"That isn't something I thought I'd see again."

Tickets cost £14 to £24, start times vary.

Call 01273 328488.