The Conservatives selected a London County Councillor, Rupert Brabner, to defend the seat.
Hythe was not one of the Liberal Party's better prospects. They drafted a new candidate for the by-election: 33-year-old Frank Darvall, who had been selected as the prospective candidate for the more winnable Dorset East. He had been the Liberal candidate for the Ipswich Division of Suffolk at the 1929 general election and for the King's Lynn Division of Norfolk at the 1935 general election. He was President of the National Union of Students from 1927 to 1929.
As in the 1935 general election campaign, the Hythe Labour Party chose not to run a candidate. However, a former Labour party member did contest the election: St John Philby stood as a candidate for the newly formed British People's Party, a right-wing anti-war party that broke away from the British Union of Fascists.
Rupert Brabner served as a junior Government Minister. He died on active service with the RNVR early in 1945. Frank Darvall had planned to contest Hythe at a 1939 or 1940 general election, but never stood for Parliament again. St. John Philby also disappeared from the electoral scene along with the British People's Party, which never contested an election again.