The portrait is based on a photograph of 1860 which the Prince and Princess used as a visiting card.
One of the treasures of the National Gallery, Velázquez's The Toilet of Venus (known more commonly as the 'Rokeby Venus') was saved for the nation in 1906 after a contentious campaign.
Leonardo's famous cartoon, The Virgin and Child with St Anne and St John the Baptist is a full-size drawing for an altarpiece that was never realised. It was presented by the Art Fund in 1962 after a massive public fundraising campaign.
The Art Fund has also helped to buy the Bridgewater Titians. Diana and Actaeon and Diana and Callisto were bought jointly by National Gallery and National Galleries Scotland.
