Simon is one of the world’s most sought-after and charismatic singers, noted for his versatility and highly charged performances on stage

Particularly acclaimed for his Posa, Macbeth, Hamlet, Billy Budd and Prospero in Thomas Ades’s The Tempest, he is also noted for Il Conte Almaviva (which he has sung in Milan and Vienna under Muti), the title role in Don Giovanni (which he has performed in Ferrara under Abbado), Pelleas (which he has sung in San Francisco, Geneva, Paris and, more recently in Salzburg, Berlin and London under Rattle) and the title role in Wozzeck (which he has sung in London, Munich, Paris and New York).

His extensive discography includes Des Knaben Wunderhorn under Rattle, the title role in Don Giovanni under Abbado, Carmina Burana under Thielemann, Marcello under Chailly, the title role in Billy Budd under Hickox, Il Conte Almaviva under Jacobs and Papageno under Mackerras. He has recorded a disc of operetta arias and duets with Angelika Kirchschlager, a disc of Brahms Lieder and Schumann's Dichterliebe with Malcolm Martineau and a disc of solo arias for Sony BMG which won a Gramophone Award for Best Recital. His Songs of War, also with Malcolm Martineau, received the 2012 Solo Vocal Gramophone Award.