Something in Natalie Dessay's demeanour, plus the odd cough and even an occasional split- second break in her vocal line, suggested that not all was well with the French coloratura soprano during her Barbican concert with Concerto Köln under Evelino Pidò.

After the orchestra's perfunctory account of Donizetti's perfunctory overture to Roberto Devereux, she began with the heroine's opening scene from the same composer's Maria Stuarda. It was a careful if contained performance in which Dessay's customary precision in fast passages overrode a hint of cloudiness in her tone.

Her extended sequence from Bellini's I Puritani went better, with the considerable actress in Dessay suggesting Elvira's tenuous hold on reality with a skilfully selected range of moonlit half-tones. Yet there was little exhilaration in the cabaletta, which needs some sense of optimism, however illusory.

Her second half began with Gilda's aria Caro Nome from Rigoletto. Again, the vocalism was scrupulous and often imaginative, with a free and easy approach to the cadenza that suggested that Dessay had explored it entirely afresh. Her tone was flowing more liberally as she launched into Violetta's big act one scene from La Traviata. Once again, there was an in-depth musicality at work and a fine technical command that took in all the written notes as well as the odd stratospheric interpolation; but her overview of the character was self-conscious and curiously awkward.

The orchestra's main contribution to the programme was the Cherubini Symphony, a piece on the dull side of worthy and too long in this context. There was some poor tuning from the band during the course of the evening, while Pidò's extravagant gestures regularly produced no more than routine results.