British writer, editor, art dealer, and lecturer. Originally he trained to be a painter, studying at the Slade School. In 1949 he moved to France, where he lived with Douglas Cooper in the Château de Castille, near Avignon, which they turned into a private museum of Cubist art. Richardson became a friend of several leading artists, above all Picasso, whom he saw regularly during the 1950s: ‘I had already envisaged writing a book about him, and so, whenever possible, I noted down his answers to my questions, as well as scraps of his conversation.’ After quarrelling with Cooper (as many people did), Richardson settled in New York, where he worked for Christie's, 1964–72, and subsequently for other leading firms in the art trade. From 1981 to 1991 he was editor-at-large to House and Garden, and from 1990 to 1994 he was contributing editor to Vanity Fair. In 1995–6 he was Slade professor of fine art at Oxford University. Richardson's literary output has included brief but highly regarded monographs on Manet (1958, revised edn 1982) and Braque (1959, in the ‘Penguin Modern Painters’ series), as well as various articles, but all his previous writings have been overshadowed by his magisterial Life of Picasso, the first volume of which (covering the period up to 1906) appeared in 1991. This was immediately acclaimed not only as the essential source on Picasso's early life, but also as one of the most impressively thorough biographies ever devoted to a major artist. The second volume (1907–17) was published in 1996 and the third (1917–32) appeared in 2007.