The story of these paintings is well documented after about 1800, the first Yusupov inventory on record is 1839 however. They are recorded in an auction in 1760 and believed by the NGA to have been painted 1660. Joseph Widener's father, Peter A B Widener, started the collection, developed the trolley system in Philadelphia, and became the richest man in the city. The portraits only left Russian once, in 1895 (I think) for an exposition in Holland. PAB heard of them and in 1905 took his yacht through the newly opened Keel Canal to St. Pete to see these paintings. His offer to buy them was refused. His son, Joseph, knew of them from that. When their presence in London hit the headlines, he went there and bought them in 1921 on contestable terms which is another story.