Maxwell, a friend and supporter of John Horne Tooke at the Westminster election of 1796, joined the Whig Club on 11 Apr. 1797, being then resident in Piccadilly. He supported parliamentary reform at the Crown and Anchor, 18 May 1797, subsequently married the daughter of a prominent Foxite, and on 7 May 1799 joined Brooks’s Club. After the death of the 8th Duke of Hamilton in 1799, his became the foremost interest in Linlithgow Burghs. He contested the district unsuccessfully in 1802. His brother Patrick urged him to contest a vacancy for Coventry in 1803, but he demurred. He was again defeated, despite Fox’s anxiety to see him in Parliament and his gaining the burgh of Peebles, in 1806.
Maxwell was a staunch supporter of opposition in Parliament. On 11 June 1807 he sent Viscount Howick a list of Scottish opposition Members to circularize for attendance.
In January 1810 he was summoned from Brighton to muster for opposition on the address and on 17 Feb. dined at the Whig leader George Ponsonby’s.
Sure only of Linlithgow, Maxwell declined a contest in 1812; in 1818, after failing to regain Peebles, he was defeated. His friends thought he should have avoided the contest: ‘he is not rich and is rather embarrassed, and ... he is no public speaker, though he is a very faithful and zealous adherent of the opposition’.
