Visual art had Britart, pop music had Britpop and now, according to this London Sinfonietta concert, we have a group of Young Brits in classical music. But there was no sense of orthodoxy in this diverse collection of premieres from seven British and Irish composers.

There was an emphatic contrast between the two world premieres in the second half: James Saunders's #200203 and John Hails's Lovesongs. Saunders's piece is part of a huge, open-ended project. Each performance of any part of the "#" series is a unique event, and the number in the title refers to the date of the performance. In #200203, tiny, evanescent sounds - like the whisper of a bow on the upper part of a violin - made the audience focus on minuscule changes of timbre and dynamic. Every sound in the auditorium became a part of the piece. Saunders's music turned listening into a dangerous and invigorating experience.

For John Hails, however, music is about noise. Three movements from Lovesongs were essays in proliferating complexity, as memories of music by Wagner and Berg were obscured by dense layers of counterpoint. Conductor Pierre-André Valade and the Sinfonietta created a distinctive soundworld for the piece, but these Lovesongs still sounded like fraught and anxious answers to the challenges of music history. If Saunders's piece was released from tradition, Hails's was bound to it.

Donnacha Dennehy's A Game for Gentlemen Played by Thugs was another kind of release: a maniacal riff for oboe, trumpet and harpsichord. Bryn Harrison's In Nomine after William Byrd was a hallucinogenic fantasy.

But the most ambitious music on the programme came from William Attwood and Tansy Davies. Attwood's En Este Sitio ... created a chaotic energy with its memorable musical gestures, like screeching string harmonics and ringing glockenspiel notes. Davies's The Void in This Colour contrasted an elemental dance with a mysterious chorale. The brutal juxtaposition produced a weird friction, like the vibrating borders between the colours on a Rothko canvas. The piece was inspired by the idea of the edges of a flat earth. After the final contrast, the music seemed to discover a place beyond the limits of its world, in a limbo of low string sounds and a lonely, bell-like piano cluster.

This concert is broadcast tonight on Radio 3 at 11.30pm.