Music: It may be on the South Downs, but spare us the horseplay

When the curtain comes down it usually means the show is over. But not on the opening night of Glyndebourne's new Le Comte Ory, when the director, Jerome Savary, made it an occasion for the most grotesquely self-satisfied display of exuberant luvvery I've ever writhed through in an opera house. He hugged the cast. He kissed them. He proposed to them on bended knee. He all but cartwheeled round the stage. No, we would not leave - for Savary was having a good time, and wanted us to know it.

I just wish I could have shared his delight in a production that seemed to please the audience (especially post- picnic) but struck me as a pretty feeble response to the vitality and (genuine) fun of a piece that doesn't surface much these days but played a major part in Glyndebourne's history. Back in 1954 the company staged a famous production under the conductor Vittorio Gui which played at Edinburgh and was preserved on a recording that remains, albeit in mono, the best around. It sets a fearsome standard; and maybe that's why Glyndebourne has kept away from the piece for so long, even though Ory is perfect material for a South Downs summer evening.

Frothy, feisty, radiant with charm, it was the last of Rossini's comedies, written for Paris in the 1820s. And while it doesn't quite shine with the brilliance of Il Barbiere di Siviglia, it's a clever score with a machinery that operates on a grand scale, extending ideas through long, complex ensembles and playing every trick in the composer's book - from accumulative crescedi to false finales - with unflagging spirit. But it's also a piece that makes the particular stylistic demands of a hybrid.

Roughly half its music was excavated from an earlier score, Il Viaggio a Reims. Its comic temperament is part-Italian opera buffa, part French opera comique, treading a fine line between vaudeville and irony. And though the story isn't subtle - Act I: an attempted assault on the virtue of a castleful of women while their menfolk are away at the Crusades. Act II: another attempted assault on the same castleful of women - Rossini's music elevates potential slapstick into pure craft. Because Count Ory (a rake) spends most of the opera in disguise and half of it dressed as a nun he comes complete with musical calling cards (resounding top Cs and a little signature tune) to keep the audience in touch with who he actually is. And in Act II there's a bizarre, gender-bending bed scene where Ory (still the nun) thinks he's making love to the Comtesse Adele but is actually coming on strong to his page-boy Isolier (sung by a woman), who is up to no good with Adele himself (herself). Confused? Well, you're entitled to be: but somehow Rossini's score sorts it all out in a trio of ravishing beauty that could be Berlioz had Berlioz got round to such things in 1828.

So here we are, a fascinating and enchanting piece, perfect for Glyndebourne - and it gets the sort of staging that would barely credit Wexford in an off year. The movement is clumsy, the jokes are poor, the business repetitive. You get one gag about pulling off Count Ory's left boot (not especially funny), then you get it again with the right (not funny at all). On comes a pantomime horse, briefly and pointlessly. Then a while later, on it comes again. Ditto.

It's not that I'm against horseplay: in something like Ory it's to be expected. But so is a degree of imagination, of sharp-minded invention; and Savary (working in Britain for the first time after a long, perhaps too long career in Europe) doesn't provide it. Glyndebourne would have been better served by someone like Richard Jones, who would have crazed things up but with some bite.

Musically the first night was a touch uncertain. Andrew Davis conducted with ever-smiling vigour, and most of the cast had the vocal idiom in their blood. There was an inspiring British debut from the French soprano Annick Massis, whose secure, soaring Adele was one thing that made this Ory worth struggling through the South London traffic for. But the promised tenor, Tracey Welborn, had withdrawn from the production, and replacement Marc Laho was disappointing: pleasant in that narrow-focused, slightly bleating French way, but unsettled technically. Ory demands a light but characterful fluency, with ringing top notes and a clean-cut coloratura. Laho struggled. It was effortful. And though the second act felt easier, it didn't compensate.

Rossini's massive international success during the early 19th century was one of the reasons why the operatic career of Franz Schubert barely got off the ground. No one in Vienna wanted to hear the German singspiels he produced in quantity during the 1810s and 20s. In the circumstances it's remarkable that he persisted and, in 1823, completed his eighth opera: another singspiel called Die Verschworenen (The Conspirators), whose comic story of a battle between the sexes in Crusader times oddly prefigures what Rossini would be writing a few years later. It was never done in Schubert's life and remains a rare work. But last weekend it surfaced in concert at The Proms and reminded me of another reason (nothing to do with Rossini) why the composer's attempts at opera failed. He had no theatre sense.

In fairness I should say that some Schubert scholars would disagree; and one of the most distinguished, Brian Newbould, pleads for Die Verschworenen as something with variety of pace and lively momentum. But personally I don't find that; and the "consistency and homogeneity" which Newbould praises seems to me one of the opera's chief problems. All the elements fit together with too seamless and smooth a continuity to allow any real sense of dramatic contour: of rise and fall, tension and release. My ear longs for the score to jolt, to stop short, to surprise me. And it doesn't.

It follows that this is a piece I'd never want to see on stage. But in concert it's a gentle, undemanding joy, and this performance by the Orchestra and Choir of the Age of Enlightenment under Nicholas McGeegan was immaculate. Done without the spoken text (no loss), it had spirit, charm, and well- judged soloists in Hillevi Martinpelto and Judith Howarth. A good case for the score, so far as you can take it.

Rossini was also presumably the reason why Andrew Davis wasn't at the Albert Hall to conduct his own BBC Symphony Orchestra for the Proms' opening night. Instead it was Bernard Haitink, whose first intentions with Beethoven's Missa Solemnis - the sole work on the programme - seemed patrician, heavy. But if ever a performance flowered in mid-course, this was it. And it flowered with a vengeance, into a dynamic and compelling performance with precise but unpedantic playing, flawless solo entries, and a sense of overall structure (always Haitink's strong point) as clear-sighted as it was controlled. The chorus discipline was stunning, with impeccable attack as sharp as a machete. And the whole thing sent me to the record catalogue to check whether Haitink had ever committed the Missa to disc. He hasn't. He should.

'Le Comte Ory': Glyndebourne (01273 813813), tonight, Wed, Fri & in rep to 23 Aug.