Music: The perfect Handel for the new Britain

Semele Coliseum, London Idomeneo Barbican, London Felicity Lott Wigmore Hall, London

The death of the Princess of Wales had cultural consequences beyond her funeral's enhancement of Tony Blair's reading skills and John Tavener's profile. Her life made the stage - and in surprising contexts, like the production of Handel's operatic oratorio Semele that played Aix and Flanders last year, and opened this week at the Coliseum.

It is a stylish show: directed by Robert Carsen (responsible for ENO's last Midsummer Night's Dream), designed by Patrick Kinmonth (responsible for nothing much in Britain, but that will soon change), and part of the new approach to Handel which has swept his once-forgotten operas into standard repertory. There are various reasons why we see so much Handel these days, not least a new model army of countertenors to take over the castrato roles that never really worked with trousered women.

But above all, the return to repertory has been driven by stage directors like Nicholas Hytner and Peter Sellars who rethought (and reinvented) the conventions of late-baroque staging which had proved so troublesome. In their hands, the tyranny of the stand-and-sing da capo aria, the very tightness of its formal constraints, became a source of energy. And in the process they grasped as never before the "tone" of these pieces - caught in a peculiarly 18th-century manner between irony and pathos, passion and whimsy.

Carsen's Semele does likewise. It's a wonderfully considered piece of work that holds the comedy and tragedy in seamless balance, with a sparing beauty that builds memorable stage tableaux out of almost nothing. But its USP is that it sets the story - of a foolish girl who falls self- destructively in love with Jupiter - in a 20th-century royal household that looks very much like the one at the end of the Mall. Semele becomes a sacrificial innocent embroiled in a monarchic wedlock mess. And when she dies, collapsing at the foot of the throne while the court looks on, the resonance is obvious.

Or at least it was when I saw the show a year ago. Now Diana's death has faded into history, the resonance is, maybe, muted. But it's still profoundly touching: not at all the Gilbert & Sullivan romp you'd expect from a Semele that blows the odd raspberry at the British Crown.

Rosemary Joshua takes the title role with an alluring (not to say revealing) tenderness that plays down the comic vanity of numbers like "Myself I shall adore" and enables her to die a truly sympathetic death. If she hasn't the pin-sharp clarity of a true coloratura soprano like Ruth Ann Swensen (Covent Garden's dazzling Semele last time round), she none the less has all the notes, and graces them with plaintive beauty.

John Mark Ainsley's Jupiter is tasteful too - over-decorous if anything, with just one glimmer of a joke before the curtain falls. But he's immaculately sung. And Susan Bickley's Juno (aka Her Majesty the Queen) is good as well, though not so funny as when Della Jones did the crown, spectacles and handbag routines at Flanders. Then, they were outrageous. Here they seem to have been softened.

A few other things have been lost in the transfer to London, including the power of Carsen's small-scale jokes (they barely register on the enormous Coliseum stage) and some general musicianship. At Flanders, the minor roles were better cast, the chorus more disciplined, and the conducting (by Mark Minkowski) of a higher order than Harry Bicket manages here. But don't be put off. It's a fine show. And an unimpeachable example of how Handel can be lovingly reconstituted into modern theatre.

When Richard Strauss sat down and lovingly reconstituted Mozart's Idomeneo into the modern theatre of the 1930s, he wasn't doing himself, or Mozart, any favours. At that time, Idomeneo was an unknown opera. Strauss imagined that a touch of doctoring could bring it into line with current tastes. But he was wrong. The Frankenstein-ish compromise that he produced pleased no one and it disappeared into oblivion, where it has more or less remained for 60 years. But it has always had its champions. Michael Kennedy's new Strauss biography (published by CUP: partisan but recommendable) pleads for it to be done again. And last weekend at the Barbican it was - in concert, as part of a Strauss series organised and conducted by Richard Hickox.

By the standards of late-20th- century period integrity, it is a shocking business: not so much for what Strauss takes away (Idomeneo is invariably trimmed down in performance) but for what he adds. The orchestra is big and provides opulent accompaniments to the recitative. There's a new orchestral interlude in Act II that has very little to do with Mozart, and rather more with Strauss's own Aegyptische Helena. And the final insult (if you choose to hear it as such) is a luscious vocal quartet, just before the finale, that unfolds in comparably Helen-ic terms.

Throughout, the rich chromaticism of the doctored score has a stylistically unsettling, seasick to-and-fro movement between the classical and the romantic. The audience response last weekend seemed to be one great collective smirk: half-horrified, but also half-gratified that we know better nowadays.

But do we? This Idomeneo is an aberration from the truth of history. But as a piece to be performed on its own terms, it's a thing of wonder: an exotic mongrel which is bizarrely entertaining. I think I enjoyed it more than any "real" Idomeneo I've ever heard. With the fabulous Christine Brewer as the (adapted) Electra character, Pamela Helen Stephen as an Idamante of surprising substance, and Kurt Streit wonderfully direct in the title role, it was a handsome cast. They were superbly accompanied by the City of London Sinfonia and conducted with exhilarating vigour. How could anyone complain? I don't.

Nor am I complaining about Felicity Lott's Schumann recital at the Wigmore Hall on Tuesday, for all its demure reduction of the emotional currency in the songs. It was a narrative recital, put together with the pianist Graham Johnson and actor Gabriel Woolf to tell the story of the Schumann marriage. Given the passionate correlation between art and life in this particular case, I'd have appreciated more intense, full-blooded readings. Lott was rather arch, as always. But she was so elegant and lovely that I didn't mind. She was herself. It was enough.

'Semele': Coliseum, WC2 (0171 632 8300), in rep to 28 May.