On a vacancy in 1789 Trevanion, a friend and political associate of Wilkes, regained his seat for Dover, where he had a house and had built up a strong personal interest during the previous 20 years. Although he never joined the Whig Club or Brooks’s, he voted with opposition on the Regency and attended their gathering at Burlington House on 11 May 1790. At the general election the following month he was successful at Dover in the fifth of the eight contests which he fought there between 1770 and 1806.
Trevanion voted against government on Oczakov, 12 Apr. 1791 and 1 Mar. 1792, and was listed favourable to repeal of the Test Act in Scotland in 1791; but he was named in Windham’s provisional list for the ‘third party’ early in 1793 and transferred his support to government on the outbreak of war. He attended the meeting summoned by Pitt at Dover in 1794 to raise funds for national defence and subscribed £100.
The nature of the business which Trevanion conducted from South Sea House, Broad Street, where he was listed as a merchant in the London directories between 1781 and 1795 (having previously traded from addresses in Bishopsgate), is not clear, but in 1806 Charles Jenkinson, who opposed him at Dover on the lord warden’s interest, described him as ‘originally a West Indian’. Jenkinson went on to say that ‘he has dissipated whatever property he possessed and bears in other respects a very broken reputation’.
