The by-election was caused by the death of the sitting Conservative MP, Robert Crouch on 7 May 1957.
North Dorset had been won by the Conservatives at every election since 1950 when they gained the seat from the Liberals.
The result at the last general election was as follows; The Conservatives selected Lt-Col. Richard Glyn.
He had first been chosen by the local Conservatives to defend the seat at the 1945 general election, but was defeated by the Liberal candidate Frank Byers.
[2] He was the son of John Emlyn Emlyn-Jones who had been the Liberal MP here from 1922 to 1924.