The data were gathered to explain the timing of the repeal of the Corn Laws by developing and testing a model that links the economic composition of British county and borough constituencies to the voting behaviour of Members of Parliament on trade policy during the period from 1826 to 1846. The model seeks to demonstrate that electoral reform and export growth and diversification during the 1830s and early 1840s, both independently and through their influence on the party affiliation of M.P.s, raised the political cost to M.P.s of maintaining a protectionist policy, thereby contributing to the policy shift from protectionism to Free Trade. The effects of constituency economic interests and political representation on parliamentary voting behaviour; the intersection of political party affiliation and constituency interests on MPs' voting behaviour; 19th century trade policy; hegemonic stability theory vs. public choice theory. Please note: this study does not include information on named individuals and would therefore not be useful for personal family history research.