In a six-decade career, the British artist also composed and performed music, published books and was an expert on African art
The world expert on the prints of William Hogarth, James Gillray and Thomas Rowlandson was a great and colourful character
Formed a peerless photography collection for the J Paul Getty Museum and curated the landmark 1989 Royal Academy exhibition to mark 150 years of the art form
Norman Rosenthal on the life of the Greek-born German curator
Since the late 1990s there has been a strong push towards provenance research of collections and museums, and restitution of items that were looted or taken by the Nazis during their period of power