Bruhn, Siglind. Saints in the Limelight: Representations of the Religious Quest on the Post-1945 Operatic Stage. Dimension and Diversity Series, 5. Hillsdale, N.Y.: Pendragon Press, 2003.

See "A Pacifist among Bellicose Knights: Magnus of Orkney," a chapter devoted to Peter Maxwell Davies' chamber opera The Martyrdom of Saint Magnus, which is based on GMB's novel (pp. 533–46).