Sir THOMAS MOSTYN ( 1776 - 1831 ), 6th bart. , continued the family tradition in regard to the representation of Flintshire in Parliament . He was sheriff of Caernarvonshire , 1798 , and of Merioneth 1799 . He was also notable as a sportsman . He d., unmarried, 17 April, 1831 , and the baronetcy became extinct, the estates passing to Sir Edward Pryce Lloyd ( 1768 - 1854 ) who was created baron Mostyn , 10 Sept. 1831 .