Alfred Brendel / Adrian Brendel, Wigmore Hall, London

Beethoven's sonatas for cello and piano represent a unique achievement, even in his output. For a start, he more or less invented the genre, developing a range of procedures and textures to make the most of the complementary qualities of the two instruments while mitigating their disparities. Then again, with the first two dating from 1796, when he was in his mid-twenties, the third from the height of his heroic middle period, in 1808, and the last two from his late style, in 1815, they give a fuller picture of his development than the violin sonatas.

No subsequent composer has contributed to the medium anything as comprehensive as these five masterpieces, which is maybe why even Alfred Brendel has been persuaded to overcome his apparent discomfort at the residual incompatibility of piano and solo-string sound to tackle them at last. But another reason is surely the excellence of his cellist son, Adrian. The younger Brendel's exceptional security of intonation, his almost unfailing ability to hit a pitch dead centre and with the purest of tone - properly reserving wider degrees of vibrato for expressive and colouristic purposes - maximises the blend between the two instruments.

So much was immediately evident from the sonorous breadth with which the Brendels launched into the majestic introduction to the Sonata in G minor, Op 5 No 2. What became apparent more gradually was the unselfconscious naturalness with which the pair accommodate each other's rubatos; pass material back and forth with subtly personal variations; and breathe paragraphs, whole movements, as one. If such qualities helped to hold together the expansive profusion of Op 5 No 2, they proved crucial to the concentrated structure and enigmatic mood-changes of the late Sonata in C major, Op 102 No 1, in which the direction of the music can turn on a handful of notes or a pregnant silence.

The second half opened and closed with two of Beethoven's early sets of variations on tunes from Mozart's Magic Flute, with a lively responsiveness to the music's more humorous quirks in the spirit of Alfred's lecture "Must classical music be entirely serious?". In between came the great Sonata in A major, Op 69. From Adrian's eloquently shaped unaccompanied opening phrase, by way of Alfred's incisively fingered scherzo, to the propulsive momentum of the finale, it was a reading that encompassed every implication of the piece - not least that moment of calm before the first-movement recapitulation, in which time seemed almost to stand still. Good news that the Brendels are committing Beethoven's entire cello-and-piano output to disc.