Bettesworth Trevanion’s grandmother Frances Trevanion was the daughter of John Trevanion of Caerhayes, a knight of the shire, and sister and eventual heir of William Trevanion, Member for Tregony, a borough which this Member’s father contested unsuccessfully in 1784, at the instigation of Sir Francis Basset. The same patron put up the son at Penryn in 1806. Narrowly defeated by Sir Christopher Hawkins, he unseated the latter on petition and replaced him for the remainder of the session. His only significant parliamentary action was to support Brand’s motion following the dismissal of the Grenville ministry, 9 Apr. 1807, indicating that he had supported them.
Trevanion’s patron chose another Cornish gentleman to put up at Penryn in 1807, probably because of Trevanion’s uncompromising support of the Whigs. In August 1807 Trevanion’s brother married Viscount Howick’s sister. In March 1808 he offered himself, too late, at Grampound on a vacancy, encouraged by the electors’ ‘recent independent conduct’ to hope they would look to a local ‘assertor’ of their independence.
He died at Brussels 8 Mar. 1840, aged 60,
