The arms are those of Holles with those of Cavendish on an escutcheon of pretence, as borne by John Holles, Earl of Clare, born in 1661. He married his first cousin, Margaret, 3rd daughter and co-heiress of Henry Cavendish, 2nd Duke of Newcastle-upon-Tyne. As a result of this, after the death of his father-in-law, he was himself created Duke of Newcastle in 1694. He died at Welbeck, one of his seats, in 1711 as a result of a fall from his horse, whereupon the dukedom became extinct. Welbeck and the other Cavendidh estates he had inherited from his wife's family he left to his daughter, whose descendants became the Dukes of Portland, but the Holles lands he left to his nephew, Thomas Pelham, who was created Duke of Newcastle in 1715.