Nash Ensemble, Purcell Room, London

The importance of Oliver Knussen and Alexander Goehr, composers whose 50th and 70th birthdays respectively the Nash Ensemble has celebrated at the Purcell Room these last two Wednesday evenings, is measured by the fact that new music would not be the same without them. Born a generation apart, they've not only taught a generation of composers in their turn, but also, through their creative example, challenged the insularity of British music.

Knussen's range was well demonstrated in a composite portrait in the first of the two concerts, where his influential early works shared centre-stage with scores by distinguished pupils. Clarity and precision shone through the varied parts ("Autumnal" for violin and piano, "Sonya's Lullaby" for piano, and "Cantata" for oboe and string trio) of his Triptych.

Like a nurturing force, these qualities found echoes in very different scores by Simon Holt and Julian Anderson. Both in their own ways aphoristic, Holt's A Song of Crocuses and Lightning, and Anderson's Poetry Nearing Silence delivered their message in short bursts of bright ideas, implying unspoken worlds in the former, and in the latter, the doubleness latent in every kind of humour. Mark-Anthony Turnage's Cantilena broke new ground in its use of the oboe, hitherto rarely associated with this composer. Kenneth Hesketh's tidy transcriptions of Debussy's two Arabesques, tailored to the Nash's line-up of harp, woodwind and strings, made a soothing opener.

There was more Knussen the following Wednesday: his Ophelia Dances, doubtless included as a neat tribute to Goehr's long-time champion in his other role as conductor. Elsewhere, a broad historical outreach was entirely typical of the older composer, and a world premiere, Reflections on Stravinsky's Pastorale, for violin and wind quartet, showed his taste for refitting the past to the present is as keen as ever. To the Russian master's touching, neo-classical Pastoral, Goehr added a solo violin prelude (named "Dushkin" after Stravinsky's violinist friend) and a blithe rondo-finale that tied the ribbon around the parcel. With no attempt to match the style of the original, yet drawing on its figures, he achieved a seamless match of old and new, no less so than in the Kafka song-cycle The Law of the Quadrille, solemnly delivered by Roderick Williams.

From then on, a pair of 20th-century classics preceded Goehr's Quintet, Five Objects Darkly. Fleet and buoyant in Stravinsky's Three Pieces for string quartet, the Nash players gave a sonorous reading of Dallapiccola's Piccola Musica Notturna in its chamber version. For the quintet, Goehr again referred to historical sources (Schubert Dances and a Mussorgsky song) but in a way that dissolved them in an often mysterious yet always compelling discourse. Surprises kept arriving right to the last double bar, just as we've come to expect from this composer.

Nicholas Williams