In Victoria Wood's original BBC1 series there was only ever half an hour in total of the spoof soap opera Acorn Antiques.

And yet in 2005, some two decades after they first appeared, those slight sketches became the basis for a fullscale West End musical. Miss Babs the posh shop-owner, her loyal assistant Miss Berta, the forgetful Mr Clifford and of course Mrs Overall the impossibly rickety cleaner: all were brought creakingly to life in the ultra-slick world of musical theatre.

Under the direction of Trevor Nunn, and with Julie Walters once more in the role of Mrs Overall, it sold out its entire 16-week run. "When I started thinking about turning it into a musical, what I didn't quite realise was how wedded people are to those characters," says Wood, who wrote both the words and the music for the show. "I suppose it was the first spoof soap and the first send-up of all those wobbly cameras, shaky sets and actors forgetting their lines. In 1985, when Acorn Antiques started, everybody knew about how laughable Crossroads was, but no one had ever articulated it before. Suddenly it just took off and became a bit of a phenomenon."

Now Wood is personally directing a scaled-down touring version of Acorn Antiques The Musical. And stepping into the iconic pinny of Mrs Overall is Ria Jones, who last appeared at the Theatre Royal in Anything Goes.

"I was originally up for the role of Bonnie, the tall glamorous long-lost triplet," says Jones, "so I was really surprised to be recalled as Mrs Overall. I used to know all the words to the sketches - Julie Walters was hysterical. This was the first time in 25 years that I've screamed and then cried about getting a part."

In Wood's typically far-fetched plot, the future of Acorn Antiques is threatened by the development plans of The Guilty Bean, the world's second-biggest chain of coffee shops. If the anonymous retail corporation does take over, will the faithful staff lose their jobs? Will Mr Clifford's memory return? And will Mrs Overall be able to tap-dance while holding onto her trademark teatray?

"There's a number that closes Act 1 which we did on the Paul O'Grady show three weeks ago called the Tip Top Tap," explains Jones, "and the opener is a spoof of All That Jazz from Chicago.

"In the final scene Mrs Overall appears via a lift wearing diamante rubber gloves. It's camp with a capital C."

The West End version included a long, self-referential opening section in which the original stars of the axed Acorn Antiques show rehearsed the stage version. This touring production cuts the preamble and goes straight for the spoof, replete with all the missed cues, fluffed lines and preposterous acting that made the TV sketches such a hit.

"The telephone rings at the wrong time, handles come off drawers, and Mrs Overall comes on with the wrong line at the wrong time," says Jones. "Last week the slash curtains got stuck and we had to stop the show for a minute. The audience all laughed their heads off 'cos they thought it was part of the show."