Going a Journey, John Woolrich's latest commission for the Birmingham Contemporary Music Group, takes its title from William Hazlitt, whose 1822 essay On Going a Journey extolled the rewards of the unmediated aesthetic experience. Hazlitt's concern was the appreciation of nature in solitude, but his idea applies equally to works of art.

So Woolrich's 20-minute piece comes without elaborate explanations or literary subtexts - it's intended to be approached as "absolute" music. The quirky, bottom-heavy instrumentation - there's no violins or upper wind among the 16 players, but both a contrabassoon and a tuba - generates a darkly mysterious atmosphere in which the musical journey itself matters more than the arrival. It's strangely compelling.

The first performance, conducted by Oliver Knussen, was marvellously assured. Knussen and BCMG also revived Jonathan Lloyd's Waiting for Gozo, originally written for the London Sinfonietta in 1981, and still sounding marvellously fresh, texturally transparent and slightly crazy in its obsession with a three-note motif. But Richard Causton's The Persistence of Memory, from 1995, had worn less well; its delicate tintinnabulations and elaborate polyrhythms run out of steam.

Knussen delegated some of his conducting duties to Ryan Wigglesworth, who took charge of Birtwistle's feisty little Cantus Iambeus. Wigglesworth also introduced Walpurgis Night, by 23-year-old Richard Bullen, which won last year's composition prize at Birmingham University. Bullen's rough-hewn sonorities are striking, and if the piece is sometimes too thickly scored and the dramatic shape of the work (inspired apparently by the second act of Who's Afraid of Virginia Woolf?) a bit diffuse, there's a real musical imagination at work.