 Lord Arran therefore "de jure" succeeded on his brother's death on 5 November 1745 as 3rd Duke of Ormonde in the Peerage of Ireland, but was never aware of so succeeding.As such, he was the fourth and last member of the Kilcash branch of the family to succeed to the titles.In 1721 he was allowed by act of the English Parliament to buy back the family estates that had been forfeited under his brother's attainder.