Peter Pan, King's Head Theatre, London

The intimate and inimitable King's Head - London's first pub theatre - is not, because of its cosy dimensions, the ideal venue for a piece that requires aeronautical antics. Any actor fool enough to be strapped into a harness at this address would run the severe risk of concussing himself and/or members of the audience. But though Peter Pan and the Darling children create the illusion of flight merely by standing on hydraulically rising pedestals and stretching out their arms, Stephanie Sinclaire's delightful production - of her own adaptation synthesised from J M Barrie's various versions of his self-invented myth - is uplifting in other ways.

For a start, it's always a pleasure when a small theatre plays paradoxical host to a proverbial cast of thousands, and here the hordes of pirates, mermaids, Lost Boys and Indians who swarm over the pint-sized, greenly glinting Never Land conjure up a sense of magical absurdity.

Then again, this Peter Pan can lay claim to be pioneering. In 1950, roughly halfway between his hit shows On the Town (1944) and West Side Story (1957), Leonard Bernstein wrote the score for a musical revival of the Barrie classic. It starred Jean Arthur, who turned 50 during the run, as "The Boy Who Would Not Grow Up" and Boris Karloff, better known for portraying Frankenstein's Monster and Dr Fu Manchu, as Captain Hook. Neither of them was up to snuff vocally. Of the six songs written by Bernstein, four were performed in cut versions, while his incidental music was dropped in favour of the work of another composer.

So the King's Head show is the first time that the score - replete with "Hook's Soliloquy", a number written for a tour that never came off, and "Dream With Me", a closing song that failed to make it into the original production - has been performed in its entirety in a full staging. The tunes are lovely; the wit (Bernstein was his own lyricist) is deft and mischievous; and the new arrangements by Mike Dixon, which orchestrate the music for piano, cello and (alternately) clarinet, piccolo and flute, combine breadth and crisp clarity, managing to project everything from dreamy sensuality to the tongue-in-cheek attack of Tiger Lily's Indian Dance with her Braves.

Hook - brilliantly played with a flamboyant, nervous energy and drolly self-guying swagger by the hilarious Peter Land (who doubles as a neurotically sly and cowardly Mr Darling) - enjoins his comrades to "Eat blood!/Drink blood!/ Dream blood!/ Think blood!" in the cod blood-curdling "Pirate Song", while in his furious mock-operatic solo, he bewails the fact that, though he'd always fancied making a big, showy dying speech, now that he's actually confronting death, there's just no time for it. With shells for bosom-covers, the delicious Mermaid Chorus sing solipsistically of the lazy, hazy sea-and-sand delights of an island where "Troubles don't exist/ No one is a pessimist..."

But Bernstein's score does not do justice to the darkness and tragedy in a piece where the title character is the arrested victim as well as the buccaneering beneficiary of his defensive refusal to accept the responsibilities of adulthood. Peter and Wendy are very well played here by Katherine Kastin and Lisa Holliman respectively - the former signalling the pain of self-exclusion, the latter the wistful frustration of flirting with a hero who is determined to treat her as an underage mother-figure and to remain clueless about more hormonal forms of love. Bernstein gives Wendy some beautiful songs of precocious awakening, but the finale "Dream With Me" is a dramatic fudge that pretends that, in dreams, the two of them will be able to enjoy the kiss never taken, the love never acted upon. Listening to this false consolation, I was reminded how, in the celebrated Trevor Nunn/John Caird version of the myth, Barrie was himself a character who pointed out, at the end, that Peter had "ecstasies innumerable that other children can never know; but he was looking through the window at the one joy from which he must be for ever barred".

To 14 January (020-7226 1916)