Painter, etcher and teacher, born in Hamilton, Ontario. He attended McMaster University and Ontario College of Art, Toronto, 1945–7, where he was influenced by John Alfsen and won a gold medal. Left to study with a scholarship at Royal Academy Schools, London, 1948–9, and was then at Royal College of Art, 1949–52. An early influence was Francis Bacon. In 1957 Thomson studied with Oskar Kokoschka, who called him the best painter of his generation. Thomson travelled on the continent and from 1949 he held various teaching posts; from 1973–84 at Central School of Art and Design he kept life classes going when they were unfashionable. Showed at RA and elsewhere in group exhibitions and had numerous solo shows in Britain abroad. Completed a number of BBC Television programmes on art.