Anthony van Dyck, Double portrait of George Villiers, Marquess and later 1st Duke of Buckingham, and his wife, Katherine Manners, as Venus and Adonis (1620-21)- The Eric And Marie-Louise Albada Jelgersma Collection, Christie’s, London, 6 December. Estimate: $2.5m-$3.5m: What does a fashionable aristocratic couple in the 17th century need on one’s wall? Why, an enormous double portrait in the guise of Venus and Adonis, of course. Once thought to be a portrait of Rubens and his wife, since its rediscovery in 1990 this early work dating from Van Dyck’s first visit to England has been recognised as depicting Villiers and his wife. It is the only known example of a mythologising portrait by Van Dyck on such a grand scale, but is it a flamboyant marriage portrait? Or was it, as the expert Jeremy Wood posits, completed later perhaps as a loving memorial, after the duke’s assassination in 1628, commissioned by his grieving widow? Courtesy of Christie's