Cambridge: BA, PhD (1956-62). Glasgow: Lecturer (1963-66). Oxford: Lecturer (1966-89), Reader (1989-94), Coulson Professor of Theoretical Chemistry (1994-2004). Fellow of Royal Society (1989). Visiting professorships: Jerusalem, Paris, Grenoble, Colorado. Invited lectureships: William Draper Harkins (Chicago), Condon (Colorado), Tilden (Royal Society of Chemistry), Boys-Rahman (Royal Society of Chemistry). Conference Chairman: NATO ASI (1977, 1979), Royal Society Discussion (1996), Faraday Discussion (2004).