 In 1800, his mother was created Baroness Dufferin and Claneboye of Ballyleidy and Killyeagh in the Peerage of Ireland, with remainder to her heirs male.After her death in 1807, he succeeded her as the 2nd Baron Dufferin and Claneboye.Blackwood was a Member of the Parliament of Ireland for Killyleagh in County Down from 1788 until the Irish Parliament was abolished with the Act of Union in 1801.