it had been the semi-rural manor of marylebone belonging to his wife's ancestors, the dukes of newcastle. this passed from margaret holles, née cavendish, daughter of the 2nd duke of newcastle, to her daughter henrietta cavendish harley. at the death of henrietta's husband, the 2nd earl of oxford and earl mortimer, in 1741, this new harley estate passed to his only daughter, margaret cavendish harley, who in 1734 had married william bentinck, 2nd duke of portland. it thus became known as the portland estate, and passed to successive dukes in the family. in 1879, the 5th duke of portland died without issue and his estates were divided between his sisters, according to the terms of the 4th duke's will, and his cousin, who succeeded him as the sixth duke. the estate eventually passed to the last surviving sister, lucy ellis, who was the widow of the 6th lord howard de walden and has remained, subject to own trustee-imposed protective restrictions, in that cognatic branch of the same family since. this marked its second cognatic succession, i.e. through women.