Mostyn, a Hanoverian Tory, forced a Jacobite sheriff of Flintshire to proclaim George II.Cheshire Sheaf (n.s.), i. 18-19. Though more interested in literature than in politics, he took a leading part in the Tory preparations for the Flintshire elections in 1734Add. 32688, f. 332. when he succeeded his father as knight of the shire, consistently voting against the Administration. In 1741 he stood down by agreement, declining pressing invitations to stand for Flint Boroughs in view of the heavy cost of the previous election there, towards which he had contributed over £2,000. Resuming the county seat in 1747, he continued to sit for it unopposed as a Tory till his death, 24 Mar. 1758.
