During World War II, unopposed by-elections were common, since the major parties had agreed not to contest by-elections when vacancies arose in seats held by the other parties; contests occurred only when independent candidates or minor parties chose to stand. In keeping with the agreement, neither the local Labour Party and Liberal Party fielded a candidate in Newcastle North.
The Conservative Party candidate was Henry Grattan-Doyle, whose selection split the local Conservative Association. A group broke away to form the Newcastle North (1940) Conservative Association, and they fielded Sir Cuthbert Headlam as an "Independent Conservative" candidate.
On a very low turnout, the result was an overwhelming victory for Headlam, who took 71% of the votes. Returned to the House of Commons, he promptly took the Conservative Whip, and held the seat as a Conservative until he retired from Parliament at the 1951 election.
Votes
Newcastle upon Tyne North by-election, 7th June 1940
Craig, F. W. S. (1983) [1969]. British parliamentary election results 1918-1949 (3rd ed.). Chichester: Parliamentary Research Services. ISBN0-900178-06-X.