The Midsummer Marriage, Royal Opera House, London <br></br> Writing on Water, Queen Elizabeth Hall, London

Post-war marriage. It went like this?

But for some radiant writing in the Ritual Dances, during which the male dancers hang themselves by their ties, this fitful filibustering continues for four hours. Few of Monday night's sparse audience remained to see the sphere that dominates Paul Brown's designs unfold into a lotus flower. But short of bolting the doors, I don't see how they could have been made to stay. Diluted Magritte sits ill with imagery commonly seen on packets of incense sticks. And despite some highly disciplined playing from the orchestra under Richard Hickox, The Midsummer Marriage is not musically successful enough to distract from its theatrical incoherence.

Tippett's convoluted choral writing is best suited to the bright, white tones of a collegiate choir. Sadly, Covent Garden's "laughing children" have aged overnight to match the opera's faddish preoccupations. Though impressive at fortissimo and pianissimo, the augmented chorus have difficulty navigating the dynamics between; especially when the only available route is a nippy fugue. But it can't be easy singing about renewal when you're swaying like extras in a photoshoot for machine-washable linen. I didn't know who to feel more sorry for: the men who have to undo their shirts as though waiting for a stethoscope, the women who must swoon dreamily while kneading their partners' exposed bellies, or me, for having to watch what resembles an orgy at a convention of retired biology teachers.

Among the leads, the best singing comes from Cora Burggraaf (a scintillating Bella with natural ping), and Will Hartmann (a lyrical Mark). As He-Ancient and She-Ancient, Brindley Sherratt and Diano Montague are cool and poised, offsetting the squalliness of Amanda Roocroft's Jenifer. John Tomlinson, a blustering King Fisher, sounds close to a coronary long before his character suffers one, while Gordon Gietz is strangely constricted as Jack. Elena Manistina's Sosostris combines unusual musical elegance with wap-wap-wap vibrato like the blades of a police helicopter.

Every minimalist likes to think he can write a decent set of variations. Few can. Subdividing the rhythms is not enough to sustain interest, so I was pleasantly surprised by the subtlety and depth of David Lang's Writing on Water: a setting of Coleridge, Shakespeare and Melville performed by the London Sinfonietta and Synergy Vocals under the marvellous Jurjen Hempel last weekend. Written in collaboration with Peter Greenaway, whose rapt films of the element were mixed live by their creator on three screens with calligraphy from Brody Neuenschwander, this multivalent work has an extraordinary variety of textures. Paul Silverthorne's Biber-esque viola solo was magnificent.

'The Midsummer Marriage': Royal Opera House, London WC2 (020 7304 4000) to 18 November

a.picard@independent.co.uk