Prince Jonathan and Princess Gesine Doria Pamphilj
Rank 2017

The Pamphiljs, Prince Jonathan and Princess Gesine, are the British-adopted offspring of a leading Italian noble family. They were adopted in the 1960s by the late Frank Pogson, a Royal Navy officer who died in 1998, and his wife, London-born Princess Orietta Doria Pamphilj, who died two years later. Their inheritance includes the 1,000-room Palazzo Doria Pamphilj in Rome and another palace in Genoa. There is also one of the greatest art collections in private hands, with a gallery housing some 650 works by Caravaggio, Titian, Raphael and Rubens. The estate and art would be worth several billion pounds on the open market. But as the art cannot be broken up or leave Italy, that value falls sharply. Even so, the asset wealth of the Pamphiljs should be £750m. It has been put into a trust in case of changes to Italy's low rate of inheritance tax.