The London Sinfonietta's classic recording of Birtwistle’s landmark scores, Secret Theatre and Silbury Air, is reissued in NMC's Ancora series.

"No more exciting recording of contemporary music than this has appeared for many a day. It celebrates the virtues, and the virtuosity, of the London Sinfonietta and also celebrates the Sinfonietta’s long association with Harrison Birtwistle, including three of the four most substantial works he has written for them. It is Secret Theatre that makes this new recording special." Gramophone