Of Woolbeding in Sussex; the youngest son of the second Duke of Marlborough, he was Whig MP for Woodstock (1768-71, 1818-20), Oxford City (1771-90), Wareham (1790-99), and Tavistock (1802-07). He was a friend of Charles James Fox.

CORRESPONDENCE OF Lord Robert Spencer:

Lord Robert Spencer to Thomas Creevey, [January 1806?] in The Creevey Papers: A Selection from the Correspondence & Diaries of the late Thomas Creevey, M.P. (London: John Murray, 1903)