Lady Mary Godolphin 1723-August 3, 1764, daughter of the Duchess of Marlborough, Henrietta Churchill and the 2d Earl of Godolphin, Francis Godolphin. Considered by some to be the love-child of the Duchess and William Congreve, who left his estate to the Duchess.
Mary married Thomas Osborne, 4th Duke of Leeds, on June 26, 1740. They had one child, Francis Godolphin Osborne, called Marquess of Carmarthen, who was later 5th Duke of Leeds and Secretary of State for Foreign Affairs, was born on January 29, 1751.