One of the most prolific modern composers of opera, he lives in Italy, and his love of Italian opera ids evident in his own work. Although thought of as avant-garde, and showing the influence of Shoenberg, his music often uses traditional forms such as symphony and concerto, and parodies or incorporates a wide range of styles.

His work includes orchestral, vocal and chamber music. He is also a major composer of operas, including Boulevard Solitude (1952, based on Prevost's Manon Lescaut), The Bassarids (1996, based on the Bacchae of Euripides), We Come to the River (1976, with libretto by Edward Bond), and The English Cat (1983).