Howard Riley, piano; Barry Guy, double bass and bass guitar; Tony Oxley, drums and amplified percussion.
Mandrel (12.53); Sirens (07.55); Quantum (13.40); Ingot (12.55).
Recorded in BBC studio, Maida Vale, London on 19 October 1973.
CD reissue of this material plus an extra track, can be found on Emanem 4044.