 Thynne became member of parliament for Marlborough in 1545 (and perhaps also in 1539 and 1542), and for Salisbury in 1547.A historian of Marlborough, James Waylen, states that Thynne was twice member for Marlborough before 1545.This is supported by a bond for £33 from the Corporation of Marlborough which Thynne was holding in March 1544, roughly equal to his parliamentary wages of two shillings a day for the three sessions of the Parliament of 1539 and the first two sessions of the one of 1542.