Singers who have been associated with the company include Geraint Evans , Thomas Allen , Anne Evans , and Bryn Terfel . Guest artists from other countries have included Joan Hammond , Tito Gobbi and Elisabeth Söderström . Among the conductors have been Sir Charles Mackerras , Reginald Goodall , James Levine and Pierre Boulez . The company have been led since 2011 by David Pountney as chief executive and artistic director .