Lord Yarmouth sat as Member of Parliament (MP) for Orford from 1797 to 1802, for Lisburn from 1802 to 1812, for Antrim from 1812 to 1818 and for Camelford from 1820 to 1822. In March 1812 he was sworn of the Privy Council and appointed Vice-Chamberlain of the Household under Spencer Perceval. He continued in the post after Lord Liverpool became prime minister in May 1812 after Perceval's assassination, but relinquished it in July of that year. The same year he was appointed Lord Warden of the Stannaries, a post he held until his death. He succeeded his father in the marquessate in 1822. The same year he was also made a Knight of the Garter and appointed Vice-Admiral of Suffolk, a post he retained until his death.