Music: `Carmelites' is devastating. I was on my knees

In 1950, Francis Poulenc met a travelling salesman in a railway carriage. The result was a traumatic love affair that, over seven years, proved seriously destabilising. Poulenc ended up in hospital, and with a body of work that bears witness to its author's neuroses: most obviously The Carmelites, resurrected in opera schedules around the world during this Poulenc centenary year and which duly opened at ENO on Thursday.

At face value, the connection between The Carmelites and the salesman - Lucien Roubert - isn't overwhelming. The Carmelites is an opera about nuns and, accordingly, dominated by women. By and large, the only role for men in the piece is to kill them under the auspices of the French Revolution, which took a dim view of religious communities; and one of the great scenes in the piece - one of the great scenes in all opera, with a power that disarms its inclination to absurdity - comes at the end when, one by one, the nuns march to the guillotine. The practicalities of death are dealt with off-stage; but the score notates the dull thud of the falling blade, which cuts into the anthem that the nuns sing as they go. Each time the blade falls, so the voices are reduced in number; and it builds relentlessly into one of those unsettling gestures of manipulative theatre you recall, perhaps, with outrage but experience with awe. On Thursday at the Coliseum it was devastating. I was on my knees.

And for that scene alone, Phyllida Law's production will surely count among the pick of this year's UK opera stagings. It's a clean, unfussy show that takes the structural oddness of The Carmelites - a loosely cinematic, rather shapeless sequence of enacted "dialogues" - on its own terms, rather than the terms of how lyric theatre ought to be. That leaves a consequential awkwardness in the flow from one scene to the next. But the conviction of the core performances holds everything together, and they're big performances. So big, you barely notice how modest a response to the imperatives of "grand" opera the show actually makes.

But to return to Lucien Roubert, his responsibility for The Carmelites was the atmosphere of simmering hysteria that pervades it. The religious fervour was a given: Poulenc was a reclaimed Catholic, whose return to the fold had been occasioned some years earlier by another trauma, when a friend had died (and been decapit- ated) in a car crash. But beyond the idea of faith under fire, The Carmelites is a story of individuals wrestling with fear and dealing, messily, with human weakness. Partly it's a fear of death; and there's a harrowing central scene that turns around an old nun dying badly, without dignity. But for the main character, Sister Blanche, it's also fear of life. This is a menopausal opera, dark with doubt and insecurity. And that Lucien Roubert stands behind it all is undeniable. As Poulenc said of the creative process: "You need human compost to make lilies grow."

At ENO the lilies flourish with a vengeance. Joan Rodgers as the neurotic Blanche, Elisabeth Vaughan as the old nun ranting at death, Susan Gritton as the novice Constance, and Josephine Barstow as Mother Marie give the performances of their lives: resplendent, irresistible. Paul Daniel conducts with a muscular strength that will shock anyone who goes expecting something between Suor Angelica and The Sound of Music. This is nothing of the sort. It's sui generis. And stunning.

Carpets of cowslips and the discreetly wafted odour of Chanel across the Sussex Downs mean one thing. Glyndebourne. And the season started this week on a note of manufactured controversy about Nicholas Snowman, who is now installed as General Director and issuing dark threats - or so they seem to readers of the Daily Telegraph - about New Music in the Glyndebourne diet. He wants it. They don't. But there's nothing very novel in that. And anyway, Glyndebourne has always been prepared to premiere new operas, from Britten's Rape of Lucretia and Albert Herring in the 1940s through to Birtwistle's Second Mrs Kong. For a full list you might read John Jolliffe's new Glyndebourne: An Operatic Miracle (John Murray). But take it from me that it amounts to an impressive body of work that hasn't chased away the patrons yet and won't in the future. Man shall not live by Mozart alone.

Meanwhile - and to show that the Snowman regime isn't out to frighten all the horses - the 1999 season has in fact begun with Mozart: a revival of Nicholas Hytner's stylish staging of Clemenza di Tito which, alas, is not so stylish this time round. David Fielding's designs are striking as ever, refracting the cool classicism of ancient Rome through the lens of post-modern Islington, but the combination of a steeply raked stage with costumes that inhibit movement is a gift to misfortune in anything but the most meticulously prepared circumstances.

For once, meticulous preparation - Glyndebourne's USP - is not in evidence. At Wednesday's first night people stumbled, got their skirts caught in the furniture, and generally looked awkward - with Hans Peter Blochwitz's Emperor Titus of the most awkward of them all.

In some ways Titus is a thankless role. Almost entirely passive, he spends the opera offering friendship, love and marriage to a succession of young women (some of them dressed as men) who in repayment plot against him, burn his house, and try to murder him. He then forgives them. Curtain. Whether that makes him a saint or a fool, it certainly suggests a poor judge of character.

Mozart, or course, expected us to see a saint: it was part of the brief in an opera commissioned to celebrate the new reign of a Habsburg emperor. But it's interesting that the commission specified a piece for two star singers: one a castrato and the other a soprano. Mozart allocated them, respectively, the roles of Sextus and Vitelia, who get most of the best music. The title role, by contrast, went to a mere tenor - not, at that time, a star voice-type - with music that allows comparatively few chances to shine until the final aria overcompensates, with a burst of coloratura that takes most Tituses by surprise.

It left Blochwitz sounding pretty shabby at the tail-end of an evening's singing that was fruitily direct but never quite distinguished. And he looked completely out of it, as if he barely knew the moves. When Philip Langridge took the role before at Glyndebourne, he worked hard to make the grand forgiveness truly grand. Blochwitz sat on the imperial throne and looked like someone's granny waiting for a bus.

Thank goodness, then, for an outstanding Sextus from Monica Groop (like all the soloists here, a Glyndebourne debutant) whose tenderly capacious depth of tone justifies, for once, the practice of casting a castrato role with a woman rather than a countertenor. There's also a tightly intense Vitelia from Patricia Schuman, and fine playing from the LPO under Graeme Jenkins, who conducts the whole thing with intelligence and sensitivity. But on this opening night it was still two cheers, not three, for a show that hadn't come together yet. Give it a week. And give Blochwitz (please) some top notes. Maybe then.

`The Carmelites': Coliseum, WC2 (0171 632 8300), Wed & Sat. `Clemenza': Glyndebourne (01273 813813), Wed & Sat.