Painted in 1954, L’Homme au Papillon is one of the most significant works of Jean Dubuffet’s career - rare in content, exceptional in provenance, and sublime in painterly style. That it is formerly from the collection of E.J. Power only adds to its importance: Power was one of Britain’s leading collectors of the post-war period and Dubuffet’s most important British patron. L’Homme au Papillon is a highlight of Sotheby’s Contemporary Art Evening Sale in London on 8 March.