The Natural Theatre Company have come a long away since their founding in the glory days of the late Sixties, when art, community and enormous flares dominated the counter-culture. Barely a week seems to go by without these darlings of the corporate events circuit trotting across our television screens and magazine pages performing their surreal absurdist street theatre at some international trade show or media event. Meanwhile back at head office, the other, stage-bound branch of the Naturals is in the service of Thespe rather than Mammon.

William Tell is a tale which is more about Gioacchino Rossini - he of the Overture - than it is about the eponymous Swiss apple-shooter. With a lusty disregard for anachronism and the Naturals' usual emphasis on luxurious costumes, versatile props and bizarre special effects, it is firmly ensconced in the comedy tradition dating back to medieval mummery, with big gestures and big gags. It is not an evening of 'high theatre'; it is pantomime for grown-ups, right down to a baddie who gets hissed by the adult audience with considerably more vigour than is displayed nowadays by the Gameboy generation. Another King Rat - a theatre critic - is subjected to violent, and extremely funny, humiliation; the kind of wish fulfilment fantasy which will endear this show to actors everywhere. And whilst Swiss visitors may find it hard to enjoy the lengthy parodying of their country, the 'Heidi, Hi!' approach is a definite hit with English punters.

The revue format - blending song, caricature and audience participation - does suffer the occasional drag, when a section is a little too irrelevant and too long for not quite enough return. A pastiche of Swiss slap-dancing forces the audience to endure way too much of the kind of rustic Alpine music usually only encountered on cheap package holiday 'Folklore Evenings', and then fails to deliver an effective punchline. But these are early days, and the Naturals are nothing if not adaptable and responsive to audience vibes.

The music - both Steve Edie's original score and the tunes borrowed from Rossini - is excellent, executed with zip and remarkable versatility by the cast, whose performances utilise clockwork precision to deliver the appearance of total chaos. The acting is dominated by Ralph Oswick, elder statesman - or possibly grande dame - of the Naturals, with his relaxed confidence and ease of interaction with the audience. As for Iain Wotherspoon, even when dressed as a woman he has a chameleon-like ability to blur the eye into suspending its disbelief, to conjure the impression that the multiple roles he plays are actually performed by multiple actors.

William Tell is brash, loud, silly, and utterly inconsequential. It is the perfect night out for anyone who wants to put their brain in neutral, enjoy some good tunes and some talented performers at work, and giggle a lot. And - of course - sing the William Tell Overture.

TOBY O'CONNOR MORSE