Mix up the following: Charlie Haden's Liberation Music orchestra, the late Loose Tubes, a free-improv group, a Mediterranean wedding-band and a little of the classic Miles Davis/Gil Evans ensemble, and you'll arrive at something like the Italian Instabile Orchestra.

For this tour (only their second visit to the UK) the band is joined by a similarly free-spirited musical force, the Leeds-based composer, pianist and found-objects investigator Matthew Bourne. Bourne opened the show, sitting cross-legged on an almost empty stage, quietly blowing, rattling and whistling to himself. The band came on in ones and twos, progressively adding comments, then building up with big, slurred trombone sounds and crackling trumpets and percussion to a collective thrash. The Liberation Music orchestra feel soon followed, in an emerging street-music groove with a heated Latin-brass sound, and Bourne added a George Formby-esque ukelele riff to bassist Giovanni Maier's jazzy feature.

Cellist Paulo Damiani (many of the Instabile's instrumentalists are also its composers) then conducted a richly layered work that often visited a laid-back, thickly chorded Gil Evans-like swing, with alto saxist Gianluigi Trovesi with the agile trumpeter Alberto Mandarini making telling contributions. Matthew Bourne's own piece was more abstract but bristling with ideas and energy. Bourne conducted it in flailing leaps, hops, frantically cajoling gestures and waved written instructions, peppering a poetry-reading by Martin Mayes with high flute and strings, staccato roars of percussion and trombones, and eventually driving a thrilling riff under another scalding Mandarini trumpet solo. Later on, a rearrangement of the traditional classic St James' Infirmary confirmed this band's haunting power. Often way off the map, but unstably inimitable.

· At Wesley Memorial Church, Oxford (0870 750 0659) tonight, then touring.