"Timing wise we're coming at the tail end of all those shows like Mamma Mia and We Will Rock You," says Perrin Manzer.

"But the seed idea was planted long before they existed. In the Nineties, Andrew and I were in Germany together working on Les Mis and we had a tendency to come up with really silly project ideas like 'Twister The Musical'.

"One night I got really drunk and suggested a Smiths musical. Andrew said it was the worst idea he'd ever heard."

It does, indeed, sound like a bit of a stinker. The party-time anthems of Abba and Queen may have transferred lucratively to the stage but it's hard to think of a band less suited to such treatment than The Smiths, a bunch of sensitive misfits from Eighties Manchester whose talent was for beating seven shades of misery out of the guitar band formula.

Effete yet muscular, mordantly black yet dryly humorous, Morrissey's lyrics are full of obscure passions and ambivalent couplings and, above all, isolation.

Wouldn't the wit wither, the ambiguity dissolve and the sense of alienation be crowded out by the bright spotlights, transparent storylines and chorus-line cast of musical theatre? As for Marr's distinctive guitar lines, would their rhythmic jangling survive the descent into the orchestra pit?

It seems, however, that fans of West End musicals are just as likely to cry "sacrilege" as fans of The Smiths.

Drawing on the "moods, wit and passion" rather than the biography or iconography of Morrissey and Marr, Perrin Manzer and Andrew Wale (the former the musical director, the latter the theatrical director) have taken a far from traditional approach.

"Both of us have worked a lot in musical theatre," says Wale. "So we kind of know what the rules are to break. The Smiths had their own moral world and I think the theatre's a great place to experiment with morals but we've gone for powerful images rather than a linear plot. We've built upon that sense of alienation, a sense of hope and desire that things might change. But there's also a lot of the ironic humour and a consciousness that life can be absurd."

"One of the things I've never understood," says Manzer, who's had his work cut out reworking pop classics such as How Soon Is Now? for the onstage string quartet, "is why we respond to music or art that we love by deifying it. Being a songwriter I write to express something for myself but it's part of the bargain that, if someone else sings it, they'll respond to it differently, whether it's a Mozart opera or a Smiths song.

"I guess it is our cultural tendency to idolise these people but on the other hand, you could pool ten Smiths fans and ask them what a Morrissey lyric means and get a different definition from each."

Chances are none of them will have pictured This Night Has Opened My Eyes as a trapeze act or imagined Please Please Please Let Me Get What I Want being sung from the top of a mountain of bodies.

But then Morrissey, who once memorably declared himself "the son and heir of nothing in particular", would surely be the first to proclaim the merits of artistic license.

Running until Saturday, October 22. Starts at 7.45pm, Sat mat at 2.30pm. Tickets cost £13-£22, call 08700 606650.