When these recordings first appeared Birtwistle enthusiasts were still absorbing the impact of three 1986 premieres, Earth Dances, The Mask of Orpheus and Yan Tan Tethera – works which helped to catapult a highly regarded composer into something as close to superstardom as contemporary classical music can provide. Secret Theatre, the longest of the three works, was itself a mere three years old in 1987: more than two decades on, its elaboration and refinement of basic formal and textural elements present in Silbury Air and Carmen Arcadiae Mechanicae Perpetuum (both from 1977) is ever more striking. Written between The Mask of Orpheus and the no less epic enterprise of Earth Dances, Secret Theatre really does mark a great leap forward, and this performance captures the special, pioneering dedication and enthusiasm which Elgar Howarth and the London Sinfonietta were able to summon up in those days. The recording, even with sensitive remastering, can’t give a full picture of the spatial processes at work, involving the tension and interaction between separated individuals and groups, but it is still a highly charged, eloquent account of one of the composer’s most powerful and most personal scores.

The more starkly differentiated mechanisms of the other pieces now seem like relatively unelaborated blueprints for the riches to follow, and despite the very different connotations of their titles – the Wiltshire landscape in Silbury Air, a Paul Klee canvas in Carmen Arcadiae – there are evident similarities, as well as moments which now sound unexpectedly derivative (for example, of Ligeti at the opening of Silbury Air). But that simply reinforces Birtwistle’s importance as part of the European modernist mainstream, something to which his substantial and distinctive contribution remains a thing to wonder at as he approaches his 75th birthday.