Dr. Matthias Wivel, curator of Michelangelo & Sebastiano at The National Gallery, London, and Dr. Piers Baker-Bates, author of the recently published 'Sebastiano del Piombo and the World of Spanish Rome' discuss the question of collaboration between Michelangelo and Sebastiano. Looking at several of the latter's paintings which went to Spain, they examine the significant influence the works had on Spanish painters.