Opera Werther Barbican Centre, London

Those who prefer their opera mummified often maintain that concert performances rescue it from directorial whim. Sometimes I sympathise. What staging could ever redeem the moment in Massenet's Werther when Charlotte prepares bread and butter? Any way you slice it, it's banal. In a concert performance, such as that given on Friday by Kent Nagano and the Lyon Opera, the moment passes unnoticed: a betrayal for which we can only be grateful.

Whatever critical doubts may recently have been raised over Nagano's conducting of the Halle, his relationship with the Lyon orchestra seems healthy, and the sense of theatre here was palpable from the opera's opening bars.

I imagine that, for most people, the evening's main attraction was the mezzo Anne Sofie von Otter in the role of Charlotte, the dutiful daughter who, in deference to her father, marries Albert, that paragon of petit- bourgeois propriety, in preference to the free spirit, Werther. A wonderful singer, Von Otter always looks so sensible, unlikely to succumb to opera's fine raptures. Yet she does, and it was impossible not to be moved when, defying concert decorum, she clung to Jerry Hadley's Werther, resting her head on his shoulder as Charlotte finally realises what she has sacrificed for marriage. It is a measure of Von Otter's theatrical instinct that, whenever she was "off-stage", she fidgeted nervously, as if to generate the emotional tension the music demands. Hers was an impressive performance, particularly as she negotiated Charlotte's switchback emotions in Act 3.

Yet the opera's heart beats in Werther. Hadley's tenor occasionally sounds a touch light for some of the Italian roles he tackles, but that lightness suits Massenet. His platform manner recalls certain Fifties crooners, probably with Mob connections, but the voice rings out sweet and true, with occasional hints of falsetto but surging manfully in the tumescent melancholy of "Pourquoi me reveiller?". If the opera's other characters are incidental, it was a pleasure to hear French text from French singers, notably the sweet, fluttery soprano of Virginie Pochon's Sophie, and the sulky baritone of Gerard Theruel's Albert.

I don't know that I'd call Nagano's conducting superficial or glitzy (as did one of the Sunday papers recently); enthusiastic and energetic certainly. But results matter more than podium style and Nagano got the best from his players while giving his singers room to move. The Halle's loss, if loss it is, seems to be Lyon's gain.