Complex sentence: It then was one of the Castle Howard paintings, and was only correctly identified after the existence of Gentileschi's second version in the Prado became known in England; after a sale in 1995 it is now on loan to the National Gallery from the current owner.
Split into simpler sentences: It then was one of the Castle Howard paintings, and was only correctly identified after the existence of Gentileschi's second version in the Prado became known in England. After a sale in 1995 it is now on loan to the National Gallery from the current owner.