Painted on canvas and measuring 99 x 158.75cm, the double portrait is, in fact, two paintings joined together, with the Lauderdale section signed and dated by the artist. Another version is at Ham House, Lauderdale’s London home. The painting is mentioned in a Hamilton inventory for 1704-12: 'Duke William Hamilton and the Duke of Lauderdale, the first delivering the roll of paper to the latter.'

Lord William Hamilton, brother of James, 1st Duke of Hamilton was educated at Glasgow University and in France, then settled at Court in London. In 1639 Charles I created him Earl of Lanark, and the following year he became Secretary of State for Scotland. He and his brother both fought on the royalist side in the Civil War, and after the Battle of Preston in 1648 he escaped to Holland. When his brother was executed in 1649, he inherited his titles, for the duke had only two surviving daughters and he believed that the Hamilton family must have a man at its head in such troubled times. Returning to Scotland with the young Charles II in June 1650, the duke marched south with him and was mortally wounded at the Battle of Worcester. He died nine days later. He too had no surviving sons, and at his wish his titles and estates passed to his niece, Anne, s.j. 3rd Duchess of Hamilton.