This is a weird undertaking. In a heated Big Top one finds something that is part sword-and-sorcery show, part medieval panto, part adaptation of Sir Gawain and the Green Knight. As a spectacle it is often enthralling but as a piece of narrative theatre it is appalling.
The real problem is the script by Carolyn Spedden. She uses bits of the great 14th-century poem in which the Arthurian hero Sir Gawain decapitates a mysterious green knight on the understanding that a year hence he too will have his head chopped off.
But, where the poem is a gripping test of Sir Gawain's character, the show is mainly about his prolonged quest to find the green knight's chapel.
Along the way he meets the wicked Mordred who, in a not untypical snatch of dialogue, announces "Arthur needs no help in the destruction of Camelot - he and the boys are doing a good job without me".
It's a measure of the story's ineptitude that the green knight is transformed from the complex double-figure he is in the poem into a routine baddie.
But the narrative is simply a platform for the spectacle and it is here that Charlotte Conquest's production comes into its own.
Even though it is irrelevant to the story, we get a medieval joust complete with elegantly caparisoned steeds. And, in the course of his quest, Gawain encounters lissom acrobats who shin up silken ropes at the drop of a hat.
As Michael Bogdanov proved in the 70s, it is perfectly possible to stay true to the poem while providing a piece of exciting physical theatre.
Damian Davis suffers nobly as Sir Gawain and Kate Waters does a good job both as fight captain and playing the role of a lovestruck sprite. The best part of the evening, however, is the curtain-call when we watch the horsemen galloping across the wide, muddy stage and dangling from the stirrups with great bravado. Maybe, in a phrase beloved of James Agate, they should have cut the cackle sooner and come to the 'osses.
· Until January 3. Box office: 020-7482 0115.
