The 4th Duke of Somerset was childless, and faced with the Dukedom passing by law to his first cousin once removed and heir male the 5th Duke, who was seated at Marlborough Castle in Wiltshire, he bequeathed the unentailed Seymour estates to his niece Elizabeth Seymour, the wife of Thomas Bruce, 2nd Earl of Ailesbury (1656–1741), and thus the Seymour estates passed to the Bruce family.