A highlight at Christie’s was a masterpiece of northern European mannerism by Bartholomeus Spranger. The painting had been looted by the Nazis, and was returned last month to the victim’s descendants. The painting was chased by New York dealer Nicholas Hall, but sold for six times its estimate to a Belgian collector, who is repatriating his country’s cultural history and spent £4.5 million at the sale on artists born and working in Antwerp.