The late John Richardson is so closely associated with Pablo Picasso, the subject of his award-winning biographies, that it’s hard to believe the two didn’t meet until the artist was nearing 70. Richardson, only 24 at the time, went on to collect work by Old Masters and by modern and contemporary artists who were often his friends—Picasso, yes, but also Andy Warhol, Lucian Freud, and many others. More than 50 of these works (including six prints by Picasso, a portrait of Mick Jagger by Warhol, and an etched self-portrait by Freud) go on sale this fall at Sotheby’s. —J.V.