The seed for Simon Bainbridge's latest work was planted some seven years ago, when he visited the Jewish Museum in Berlin before Daniel Liebeskind's extraordinary space was filled with exhibits. There he conceived the idea of composing a piece that would come directly from his response to the architect's creations, and which could be performed within them. The result is Music Space Reflection, which was given an expert premiere by the London Sinfonietta under Diego Masson in Liebeskind's most celebrated British building, the Imperial War Museum North.

The piece is strikingly different from anything Bainbridge has composed before. Much of his music is linear, deriving its weight and complexity from the layering of instrumental lines. But the emphasis in Music Space Reflection is on the vertical, as if to establish an aural point of reference within the dizzying geometries of Liebeskind's buildings. Music Space Reflection is a restrained, bleak processional, whose mood, as Bainbridge revealed here in a platform interview, was influenced by the sombre purposes of so many of the architect's buildings.

What begins as a halting series of chords, shared between the four spatially separated sextets of instrumentalists (all identical, with pairs of woodwind, brass and strings), gradually thaws into some of Bainbridge's typically busy filigree. Yet the music remains static and meditative, though there is a brief climax, coloured by electronic bell sounds and brass, before the piece relapses into a final silence. Among the War Museum's display cases and icons of war - a field gun, a tank, a fire tender - it made a curious, rather plaintive statement.

· Repeated tonight at Queen Elizabeth Hall, London. Box office: 0870 800 400.