Camelot, Open Air Theatre, Regent's Park, London

The musical Camelot is famously identified with the "one brief shining moment" of the Kennedy presidency. His widow let it be known that JFK was a great fan of the cast album, and, in the weeks after the assassination, there were reports of audiences stopping the show with their sobs.

But watching Ian Talbot's charming, piquantly timed revival of the Lerner and Loewe classic at the Open Air Theatre in Regent's Park, I was struck by how there's something so glamorously expedient in the show's politics that any would-be statesman would queue up to be associated with it. As Kenneth Tynan noted at the 1961 premiere, there's an analogy between Arthur's Round Table and the UN.

But then you notice the worrying malleability of the monarch's motto: "Not might is right, but might for right." Yes, but who is to say what "right" is? And the idea of his knights riding all over the world "whacking away" to snuff out wickedness puts you in mind of, well, the "axis of evil" and George Bush. Even the Kennedy connection is bogus - he'd hardly sat down in the White House before he was sending troops into Laos and Vietnam.

Yet the show is not sunk by its opportunistic admirers. Progressing from the comic insecurities of youth to pained maturity, Daniel Flynn's modest, moving and intelligently sung King convinces you that Camelot can boast a genuinely tragic hero, impaled on the contradiction between love and the new civil law he has instituted. In the early scenes, Flynn and Lauren Ward's impish, fresh-voiced Guenevere create a lovely playful sense of two royal misfits meeting as soulmates.

The arrival of Lancelot - an amusingly earnest and self-intoxicated Matt Rawle, whose long-jawed good looks verge on parody and whose French accent verges on libel - brings this idyll to a close. Not that he and Guenevere get up to much, beyond singing the naff "If Ever I Should Leave You" at each other - which may count as a crime against taste but is hardly deserving of the death sentence. Then again, I don't know...

There are some enchanting sequences. The duet where the King and Queen try to rouse themselves from their melancholy by asking "What Do the Simple Folk Do?" in such circumstances is beautifully performed here, witty and ineffably sad as each boisterous bid for imitative jollity (whistling, hornpipe-dancing etc) subsides back into regal gloom. Blundering around like someone with mild concussion, Russ Abbot provides expert comic relief as the crackpot old Sir Pellinore.

But the winning cast and eloquent band can't mask the faults in construction nor the fact that some of the numbers sound like tired My Fair Lady retreads. Arthur has a tendency to fall into the bemused "Why can't a woman learn to think?" mode of Professor Higgins. The joust won by Lancelot is staged (somewhat tastelessly) like the Ascot scene in the earlier musical. It doesn't help that Arthur's evil bastard Mordred (a bland Mark Hilton) is kept waiting in the wings till the second half, or that a whole opera's worth of drama is frustratingly compressed into the song "Guenevere". And why in a musical about a tortured love triangle are we never given a great trio?

To 4 September (0870 060 1811)