Professor Mason was previously Head of the Department of French at the University. He was General Editor of the Complete Works of Voltaire published by the Voltaire Foundation in Oxford from 1998 to 2001 and has remained ever since a member of its Comité éditorial. His former activities include the General Editorship of Studies on Voltaire and the eighteenth century (1977-96) and Presidency of the International Society for Eighteenth-Century Studies (1991-95). He is an Officier of the Ordre des Palmes Académiques and holder of the Médaille d’Argent de la Ville de Paris.
His research interests have been mainly in the Enlightenment, with particular emphasis on Voltaire. His publications include several books on Voltaire and critical editions of his works, as well as monographs on Cyrano de Bergerac and Marivaux, plus general studies of the Enlightenment.