On his nephew's death on 8 July 1779, he succeeded him as 5th and last Duke of Ancaster and Kesteven and Marquess of Lindsey and as 8th Earl of Lindsey.
On his nephew's death on 8 July 1779, he inherited the titles of 5th and last Duke of Ancaster and Kesteven, and as 8th Earl of Lindsey.