CLASSICAL: Henry Gronnier and Jean-Yves Thibaudet Wigmore Hall, London

Stepping into the shoes of an indisposed artist can, on occasion, lead to an upward leap in a career. But in the case of the French violinist Henry Gronnier, no stratospheric leap will, I suspect, occur. Admittedly, he appeared to take up the challenge of replacing the hugely gifted Norwegian cellist, Truls Mork, at extremely short notice, jetting in from New York on Concorde on Tuesday with scarcely time to draw breath. But what a pity a cellist could not have been found in this city seething with cellists for a programme of Brahms, Shostakovich and Rachmaninov, which promised to be an interesting balance of some of the cello's most challenging repertoire.

My own disappointment was particularly keen because a little over a year ago, in the BBC's Building a Library, I chose Mork out of a large field for his performance on disc of the Brahms cello sonatas and this was to have been the acid test in concert. Bad luck, too, for the pianist Jean- Yves Thibaudet, for whom this concert should have been the crowning conclusion to a set of three recitals at the Wigmore Hall, in being unable to show his sensitivity as accompanist in the early Brahms cello sonata that tends to be made or mucked up by the pianist. As it was, Henry Gronnier had to cope with an almost palpable sense of disappointment in the hall, perhaps something hardly likely to encourage a jet-lagged second string.

The programme was of course entirely changed. The concert began with Beethoven's first violin sonata, his Op 12 No 1, written in the late 1790s and dedicated to Antonio Salieri. The three Op 12 sonatas were actually published as "Sonate per il clavicembalo o Forte-Piano con Violono", in other words, for piano and violin. Balance with these sonatas is always problematic as the piano really does have all the notes, and on half stick Thibaudet threatened almost immediately to drown Gronnier. But it soon became clear that, while a musical player, Gronnier lacks the technical equipment to make much of a match for Thibaudet. Apart from being very music-bound (well, Concorde doesn't provide much time for mugging up), Gronnier's sound is thin and unfocused, the vibrato flabby, and the intonation, at times, questionable. Against Thibaudet's exuberant energy in this youthful Beethoven, Gronnier was merely going through the motions. Nerves may have accounted for this, but in Brahms' A major sonata where the violin does come into its own, Gronnier failed to provide the lushness of tone, the variety of colours that this music cries out for. Thibaudet, too, seemed struck by a bout of matter-of-factness, although in the fast section of the slow movement, his fingers certainly danced.

Cesar Franck's violin sonata might have been expected to bring solid ground to these two French artists but, again, Gronnier, with so small a sound, so little shading of phrase, and so narrow a dynamic range, merely hampered Thibaudet, even if the French pianist couldn't be entirely reined in during the turbulent allegro.