A recording of Drone Mass by the late Icelandic composer Jóhann Jóhannsson is released today by Deutsche Grammophon, performed by Theatre of Voices and ACME, and conducted by Paul Hillier. In this week's Gramophone podcast, Hillier joins Editor Martin Cullingford to recall the creative process of working with Jóhannsson, and to explore this fascinating work and the experience of recording it. Gramophone Podcasts are produced in association with Wigmore Hall.