During the 1920s, the constituency was a fiercely contested marginal between the Liberal and Conservative Parties, with the sitting MP defeated at each election.

At the 1924 general election, it saw a 92.7% turnout, a record for an English constituency.

Withnell Urban District was added from the pre-1950 Chorley constituency.

1955–1983: The St. Andrew's, St. Francis's and St. Mark's wards of the County Borough of Blackburn, the Borough of Darwen, the Urban District of Turton, and the Rural District of Blackburn.

The political parties had been making preparations for an election to take place and by the July 1914, the following candidates had been selected; A General election was due to take place before the end of 1940, but was postponed due to the Second World War.