The National Liberals came into being in 1931 when the main body of the Liberal Party were unhappy with Ramsay MacDonald's multi-party coalition National Government pursuing a policy of tariff reform. The Liberal Nationals were prepared to take the place of free trade Liberals when the latter resigned, and in doing so two separate groups evolved in the 1931 general election.
The Liberal Party divided into those who remained in the new coalition government and became the National Liberals (led by John Allsebrook Simon), and those who left and continued operating under the Liberal Party name (led by Herbert Samuel).
In 1947 the party formally merged with the Conservative Party but some MPss and candidates continued to use the National Liberal party name for elections until the 1960s. Until 1966 they continued to claim a room at the Westminster Parliament for their own use. At this point, the remaining National Liberals assimilated completely into the Conservative Party.