 He was elected to the House of Commons for Cardiganshire in 1755, a seat he held until 1761 and again from 1768 to 1791 and also represented Berwick-upon-Tweed between 1765 and 1768.He served as a Lord of Trade in 1768 and as a Lord of the Admiralty from 1770 to 1782.Lisburne succeeded his father as fourth Viscount Lisburne in 1766 but as this was an Irish peerage it did not prohibit him from sitting in the House of Commons.