Politician and soldier. One of the governors of London's Foundling School. Lord Lieutenant of Buckinghamshire then of Oxfordshire, Lord Steward (1749-55) and Lord Privy Seal (1755).

He was a brigadier general and had commanded a brigade at Dettingen in 1743. His wife was Elizabeth Trevor, whom he had married in 1732 and who died in 1761; she was the daughter of Thomas, 2nd Lord Trevor of Bromham, who had been created a peer specifically to assist Parliament get the Treaty of Utrecht onto the books in 1713.

Their son, George Spencer, became the 4th Duke of Marlborough at theage of nineteen. He was born on 26 January 1739 and died at Blenheimon 29 January 1817. During his lifetime he was Ensigny in Coldstream Guards 1755, Captain of 20th Foot 1756, Lord Lieutenant of Oxford 1760, Bearer of Sceptre and Cross at the coronation of George III, Lord Chamberlain 1762 and instituted as a Knight of the Garter in 1771. On 23 August 1762 he married Lady Caroline Russell, daughter ofJohn, 4th Duke of Bedford; she died on 26 November 1811.