WHAT A witty, whimsical, mesmerising and meltingly beautiful entertainment the American choreographer Mark Morris has made of Henry Purcell’s semi-opera. It’s a village fête, a seaside show and a surreal pageant of British eccentrics from all eras and many mythologies, rolled into one and done with winning grace.

And how audaciously Morris has refurbished this bizarre Baroque hybrid for our impatient century. Try staging King Arthur as it was done in 1691 — a sprawling historical play by Dryden, intermittently spiced with Purcell’s music — and you would end up with a four-hour show, involving parallel casts of actors and singers, costing millions (just what Covent Garden did in the 1990s).

Morris’s solution is brutal but effective: dump the Dryden. Out goes every rhymed couplet of the spoken text, and all semblance of the story about Arthur’s battle with the Saxon King Oswald. Indeed, out goes Arthur himself, except for a big, Hollywoody crown that pops up somewhere in every scene — symbol of an enduring British patriotic impulse that is gently satirised but never utterly mocked. What remains is a 100-minute sequence of vocal solos, dances and choruses on which Morris can launch his dazzlingly eclectic flights of imagination — mixing his own characterful Dance Group with seven solo singers (the ENO chorus is banished to the pit).

Even in his wildest whimsies, however, the link with the original is never snapped. Rather, it is illustrated in unexpectedly incongruous ways, as when a trio in praise of British wool is deliciously subverted by three chaps sorting their laundry, or when Purcell’s teeth-chattering Frost Scene becomes a man singing inside a fridge — a stroke of saucy genius on a par with Jonathan Miller’s jukebox in Rigoletto. The Sgt Pepper-ish bric-a-brac of zany costumes by the fashion designer Isaac Mizrahi adds to the barmy fun.

Not every scene clicks. And although Morris’s folk-infused choreography is intentionally homely — giving the illusion of ordinary Britons seizing their pleasures while they may — there’s a sameness about some pastoral scenes, notwithstanding a strenuous burst of lusty mass-lovemaking and a blissfully silly sequence of bodies cascading from wardrobe doors. But the final, virtuosic dressing of a maypole is worth the price of a ticket by itself.

The singers put over their music in fine Purcellian style. And Jane Glover conducts this masterly score with a perfect mixture of sensuality and perkiness. Purists may wince at the treatment of poor old Dryden (and Arthur). But Purcell’s fabulous tunes — Fairest Isle and all — are never upstaged.

Box office: 0870 1450200