 Under the Reform Act 1832, the constituency was allowed to survive and to keep one of its two MPs, but the boundaries were considerably extended, taking in the Wallingford Castle precincts, which had previously been excluded, and all or part of a dozen neighbouring parishes including Benson and Crowmarsh, and part of Cholsey.This change of boundaries almost trebled the population, but the effect on the electorate was much smaller.According to the reports on which the Reform Act was based, Wallingford had about 300 men qualified to vote in 1831 (though no more than 230 had ever voted in the previous thirty years).