Born London, UK, 1938. Cambridge University BA and MA. Harvard University PhD 1970. On the faculty of Tufts University 1972-2008. Fellow of the Medieval Academy of America, the Society of Antiquaries of London, the American Academy of Arts and Sciences. International Council for Philosophy and Humanistic Studies (Conseil International de la Philosophie et des Sciences Humaines or CIPSH), an affiliate of UNESCO: Vice-President 1997-1998; President 2001-2004; scientific committee for its journal Diogène 2005-2014; Honorary President 2004 — ; Union Académique Internationale in Brussels: Delegate from the American Council of Learned Societies, 1984-present; Comité des affaires internes, 1991; Bureau 1992-95; Vice-President 1995-98; President 1998-2001; Honorary President 2001–; International Center of Medieval Art, Board of Directors, 1978-84; Vice President 1983-84; President 1984-87; Board 2002-2005; Medieval Academy of America: Council, 1981-84; Vice President 1991-93; President 1993-4; Corpus Vitrearum International Board, Vice President 1983-87; President, 1987-1995; Honorary President 2000–; Corpus Vitrearum Committee for the U.S.A., 1975-present; Chair of the Editorial Subcommittee, 1982-92 and treasurer 1986-2008. Author of nine books and 120 articles.