 Conyngham was knighted in 1829, and at the 1835 general election he was elected as Liberal Member of Parliament for Canterbury, a seat he held until 1841, when he did not contest the election.He was elected unopposed at a by-election in March 1847 and held the seat until he was elevated to peerage in 1850.From 1844 to 1845, he served as first President of the British Archaeological Association, and from 1855 until his death as first President of the London and Middlesex Archaeological Society.