ウィリアム・キャヴェンディッシュ＝ベンティンク
Portland was the eldest son of Prime Minister William Cavendish-Bentinck, 3rd Duke of Portland and Lady Dorothy, daughter of William Cavendish, 4th Duke of Devonshire and Charlotte Boyle, Baroness Clifford. He was the elder brother of Lord William Bentinck and Lord Charles Bentinck.