Colleton, who unsuccessfully contested Lyme Regis in 1734, was in 1747 returned as an Administration candidate for Lostwithiel. In 1754 he paid Lord Edgcumbe £1,000 for his seat, negotiated by Administration, and in 1761 £1,500. He held neither office nor pension. In Parliament, though not prominent, he seems to have been respected: in the autumn of 1761 Newcastle considered him a possible candidate for the Chair,
Colleton had no electoral interest of his own, and in 1768 could not have had at Lostwithiel either the support of Administration or of Lord Edgcumbe, who acted with the Rockinghams. He is not known to have stood in 1768, but in 1772 was returned by Nugent for St. Mawes as a Government supporter—in the division of 9 Feb. 1773 on the naval captains’ petition he is placed among the ‘friends’ who voted against the Government. There is no record of his having spoken in the House, and he did not stand for re-election in 1774.
Colleton died 30 Aug. 1790. After his death Haines Hill and the Barbados plantations passed to the son of his cousin Charles Garth.
