Held a seat on the Board of Trade (1766-70). Named to the Privy council (1770). Ambassador to Madrid (1770-79). First Lord of Trade (1780-82). Foreign secretary under Shelburne’s administration (1782-83).
Member of Parliament from 1761 until 1770, when he succeeded his father as Baron Grantham.
Married Lady Mary Jemima Yorke (1780); three sons.