Sylvia, Royal Opera House, London <!-- none onestar twostar threestar fourstar fivestar -->

Bussell gets lost in the Amazon

Last season, the Royal Ballet pulled Frederick Ashton's full-length Sylvia back from oblivion. Almost 40 years after the last performance, lost choreography was pieced together from film and memory. Sumptuous sets and costumes were recreated, while the dancers faced exacting choreography that had fallen out of performance before they were born. Now Sylvia, which will be televised later this year, returns to repertory.

So, does it work? Sylvia is a frilly pastoral tale, a stylised return to the conventions of 19th-century ballet. Fauns and peasants dance, Amazons forswear love, gods descend to fix the holes in the plot. After the god Eros rescues the huntress Sylvia, who has been abducted by the hunter Orion, they stop off on the way home to collect a wedding dress and eight attendants in matching key-patterned tutus.

Until the celebrations of the third act, much of Ashton's choreography looks like pastiche - polished and spectacular, always pretty but rarely substantial. It takes flair, and particularly musical flair, to make it sparkle. The Royal Ballet's dancers ride Sylvia's technical demands with confidence, whipping through jumps, fouetté turns, hops on pointe. They've learnt how to pace these numbers, how to build up excitement.

They are let down by Graham Bond's conducting. Delibes's score is delightful, but it needs a lighter hand, springier rhythms, more impetus. Last year, the whole ballet looked better when Ben Pope took over the conducting. Pope is scheduled for more performances this year, which should lift energy levels.

The real point of Sylvia is the ballerina role. Ashton set out to display his muse Margot Fonteyn, who had just become an international star. He gave her seven solos, each in a new mood, all making fierce demands on the dancer's technique. The Amazon Sylvia falls for the shepherd Aminta, gets abducted, pretends to seduce her captor, appeals to the gods and celebrates her wedding. It's Sylvia's party, but it doesn't show off Darcey Bussell.

Bussell has been dancing gorgeously in this, her last season as a full-time member of the Royal Ballet, but she looks rushed in Sylvia. The lovely expansive technique is there, her line and feet are as beautiful as ever, but none of it has space to bloom. Working with the much smaller Fonteyn, Ashton concentrated on speed and on the ballerina's ability to command her stage. Bussell sprints to get her long legs round these steps, and she isn't on top of the role's dazzling contrasts. She's at her best in the slow, soft moments, pleading for help with moving simplicity.

Sylvia's best choreography comes in the last act. You can see that Ashton had The Sleeping Beauty in mind, but the final pas de deux is distinctively Ashtonian. Ashton gives his dancers grand moments, then softens into tenderness. Sylvia strikes a grand arabesque, before Aminta draws her hands up to her cheek.

The company's men get the most out of Sylvia. As Eros in disguise, Martin Harvey times his comic solo wittily, then raises his arms with real grandeur when revealing himself as a god. As Orion, Thiago Soares gives a performance pitched between seriousness and scenery chewing, while his dancing is crisp and punchy. His two slaves, Joshua Tuifa and Kenta Kura, have a gruesome orientalist number, which they dance with bold attack and we-dare-you-to-laugh energy. As Aminta, the generally bland Roberto Bolle is more alert than I've ever seen him.

The company dance Sylvia with gusto. Stuck dancing ceremonial goats (yes, really) in the wedding divertissement, José Martín and Iohna Loots give punchy performances. Bennet Gartside's swaggering Pluto pursues Caroline Duprot's big-eyed Persephone. The celebrations end with a triumphant finale, the whole cast bounding, turning, skipping through fast footwork and buoyant jumps. Much of Sylvia is slight, but the Royal Ballet look determined to give it full value.

To 21 December (020-7304 4000)