There’s a fascinating moment in Bálint András Varga’s Conversations with Iannis Xenakis (Faber & Faber: 1996) when the composer digs out a pile of exercises and apprentice scores, and describes his experiences as a student of Milhaud, Honegger and Messiaen. Anastenaria (1952-54) is not exactly a student work, but Xenakis claimed that its second section was loftily dismissed by Boulez as ‘too simple’, and the impression is created that the first two parts were left in sketch form. This world première recording of the complete version therefore comes as a surprise, and the music itself is surprising, charting a rapid transition from a relatively simple modality in the initial ‘Procession’ to a much more fragmented and diverse radicalism in the final section, ‘Metastaseis’.

Anastenaria begins by depicting a springtime ritual from northern Greece, and it sounds both primitive and tentative alongside one of his finest mature works, Aïs (1980). This is even more graphically ritualistic, a representation of Hades combining a fierce horror of death with hints of pathos and regret, of a sweetness rare in Xenakis’s music. This world première recording from 1981 is less well-defined than the others on the disc, but the performance is uninhibited and well-sustained, with a gripping sense of evolving dialogue between voice and instruments. Spyros Sakkas summons up a fantastic range of vocal effects, while Sylvio Gualda’s drumming lays down a battering barrage which the orchestra elaborates and refines.

Aïs is undoubtedly the highpoint of this programme; beside it Troorkh (1991) is relatively routine and scrappy. But Mike Svoboda does wonders with the hair-raising trombone part, and even below-par Xenakis has enough inventiveness and musical character to make for intriguing listening.