William Cavendish-Bentinck
Cavendish-Bentinck was the eldest son of Lieutenant-General Arthur Cavendish-Bentinck from his second marriage to Augusta Mary Elizabeth, 1st Baroness Bolsover. His paternal grandfather Lord William Charles Augustus Cavendish-Bentinck was the third son of William Cavendish-Bentinck, 3rd Duke of Portland, while William Cavendish-Bentinck, 6th Duke of Portland, was his elder half-brother. In 1880 he was granted the rank of a younger son of a duke on his half-brother's succession to the dukedom.