A cyclist attempts to carry his bike up the stairs into the main house at the Lyric and is stopped by an alert usher. The same cyclist then leads the waiting audience out across the road into the upstairs room of the pub opposite.

So begins this site-specific production by Cartoon de Salvo. The cyclist then turns into the troubled lead guitarist of a cover band called One Trick Pony and, after an authentic pub-rock delay of at least 20 minutes, the show eventually cranks itself into first gear.

It’s an unpromising start. A plodding version of "Mustang Sally" is followed by "Brown-Eyed Girl" and then, cringe-makingly, "We Are Family". It’s the third-rate pub gig from hell, complete with weak attempts at jokey introductions, and lame interplay between the band members.

The lead guitarist, Richie (Neil Haigh) then insists on taking a call from a mate at Heathrow who is on his way to Bangkok, while the other band members stand idly by, looking embarrassed and pissed off by turns. It continues in this vein, via two intervals, one supposedly occasioned by a technical problem, and the other, a mere five minutes later, by an emotional problem from Richie. It’s quite amusing, in a David Brent-ish sort of way, but lacks any dramatic impetus, or coherent shape, and makes you yearn for some kind of big reveal, or reversal, or trick, which will suddenly get the real show underway.

That never happens, alas, although we do get some droll moments as Richie decides that after 20 years of playing other people’s music, he can no longer stifle his own ‘talent’, and when Hayley the bass guitarist (Alex Murdoch) throws a wobbly after they play her wedding song "The First Cut is the Deepest". It’s all acutely observed, adroitly played both onstage and among the audience, and neatly spoofs many such well-meaning pub acts that can barely hold themselves together as an onstage unit, let alone in real life.

But it’s a show that stretches its one basic joke far too thinly. Cartoon de Salvo have a reputation for off-beat, ‘script-defying’ improvisational techniques, and there is considerable talent on display. As an ensemble they clearly relish theatrical danger and breaking the rules, but director Alex Murdoch allows the concept to overpower the execution, and we end up with an evening that never quite gets off the ground.

- Giles Cole