Bettesworth took the additional name of Trevanion by royal licence on 18 December 1801 when he inherited the Caerhays estate. Three days later, he married Charlotte Hosier (died 1810; age 27) by whom he had four sons including, John Charles Trevanion Bettesworth, Henry Trevanion Bettesworth (d. 1855), George Bettesworth (
RN), and Frederick William Trevanion Bettesworth (vicar of
Whitby), and one daughter, Charlotte Agnes (died 1809). His second son Henry Trevanion Bettesworth (1804–1855) married 4 February 1826 his distant cousin Georgiana Augusta Leigh (1808–1866), a daughter of
Augusta Leigh (elder half-sister of
Lord Byron) but in 1829 ran off with his sister-in-law
Medora) to the Continent, where he eventually separated from her and died in 1855. In 1830, he married secondly Susannah (c. 1800 - 1886), daughter of the
English reformist politician, Sir
Francis Burdett, by whom he had a daughter. forced to live abroad. Described as "the very
arbiter elegantiarum", he died in
Brussels,
Belgium in 1840. ==In popular culture==