King Arthur, Coliseum, London <!-- none onestar twostar fourstar fivestar -->

It may seem fanciful to suggest Mark Morris's rambunctious take on Purcell's King Arthur has its origins in morris dancing - but that's certainly part of it. That and centuries of provincial pageantry. Let's face it, the nation's heart was always to be found in village halls and on village greens all over the country. Amateur dramatics, rude mechanicals, mead and maypoles. None of it has escaped Morris. His randy vaudeville does for Purcell and John Dryden what Monty Python did for the Holy Grail. It's Spamalot with better singing and more dancing.

Back to basics, then. Back to the community centre. A naked light-stand, a row of utility chairs, and a few red drapes are all that grace the empty Coliseum stage. An artificial back wall further underlines the director's contention that "the setting is the stage" (designer: Adrianne Lobel). The performers - which Morris insists "are themselves" - arrive one by one, a prop or plumed helmet dressing up their day clothes. King Arthur's crown - last used, perhaps, in this particular society's unforgettable production of 1066 and All That - sits forlornly on one of the chairs. And we're off - with Jane Glover's vigorous orchestra and chorus, Morris's dancers, and this motley troupe of vociferous players somewhat determined to live up to Dryden's words: "Sure there's a Dearth of Wit in this dull town, when silly Plays so savourly go down..."

For the most part Morris's response to the text's archaic repetitions is naively illustrative. A series of tacky production numbers. He's tried to retain the innocence. But there's a knowingness, too. He gently, sometimes downright camply, lampoons the overtly patriotic and the tweely bucolic. James Gilchrist's robustly agile tenor defiantly sings "Come if you dare, our trumpets sound" in a gold sequinned jacket; nymphs and shepherds bring springy choreography so seemingly pointless you wonder if they are making it up as they go along.

But there is sporadic wit in, for instance, "The Chase", which creates a Brian Rixian farce of opening and shutting dressing-room doors where a variety of medieval stereotypes in bad wigs and makeshift frocks manically come and go. Then there's "Winter", whose commentary - one of Purcell's wittiest teeth-chattering creations - is delivered, by Andrew Foster-Williams, from inside a fridge-freezer. And under the heading "What Love Does" Morris prematurely brings down the curtain on a potentially headline-making orgy as if to say: "No sex, please, we're British."

Perhaps the greatest pleasure, though, is provided by Isaac Mizrahi's costuming - a riotous mismatch of periods and styles, a dressing-up and a dressing-down of every conceivable fashion statement. Victims are inevitable. The show's character - and most of the wit - springs from his imagination. When Britannia finally delivers "Fairest Isle" she does so in frumpy black satin like one of those erstwhile oratorio singers so beloved of the English.

Mhairi Lawson was that singer and her rendition was all sweetness and light. Wholesome, yes, but a bit chaste for my taste. There must surely at least be a suggestion of relish in the delivery. I should like to have heard the counter-tenor Iestyn Davies sing it. His number summoning the battle-weary heroes to Woden's Hall was splendid. It's a smashing voice and he has real stage presence.

I'd have put money on the show ending with the obligatory dance around the maypole, and it does, red, white, and blue ribbons proudly woven. The naffness on show is entirely English but the camp is all-American. It's sweet, jolly, and irritating in more or less equal measure.

To 8 July (020-7632 8300)