THIS hour-long performance by saxophonist Evan Parker and his 12-strong Electro-Acoustic Ensemble was, it is presumed, entirely improvised. The players had nothing more than a few Post-It notes to guide them.

Parker stood at the front, in the position where a conductor would be, but seemed to offer no cues or interpretational guidance.

It is therefore remarkable that this spontaneous performance, in which conventional ideas of rhythm, melody and harmony had no place, should somehow have acquired a sense of structure, a kind of arc or a musical journey from the opening, agitated solo on piccolo trumpet to a serene and utterly logical conclusion played on the Japanese sheng.

Order seemed to emerge from chaos.

Evan Parker is categorised as a jazz musician, although the only resemblance that Saturday’s performance had to conventional jazz was that it was catalysed by a sequence of solos from instruments that included piano, trumpet, clarinet, violin, double bass and sheng.Š

Collective improvisation then took over and a bank of five electronic specialists whose “instruments” were laptop computers processed and manipulated the sound, often quite subtly.

This free music idiom is not simply a get-out clause for second-rate players. High levels of virtuosity were on display, including a wide range of advanced techniques.