The arms are those of Cavendish impaling those of Boyle, as borne by William, 4th Duke of Devonshire, born in 1720, who, as Marquess of Hartington, served as Prime Minister from November 1756 to June 1757. He married in 1748 Charlotte Elizabeth, suo jure Baroness Clifford, only surviving daughter of Richard, Earl of Burlington. "Lord Hartington and his father the Duke of Devonshire were the fashionable models of goodness, though their chief merit was a habit of caution" remarked Horace Walpole. He succeeded to the Dukedom in 1755 and died in 1764.