Although this film was based on a novel by a serving Labour Member of Parliament (who had died before it appeared), it was widely regarded by critics as none-too-subtle propaganda for the Conservatives, of whom the head of the studio was a vocal supporter.
Johnnie is frequently referred to as a back-bencher. Front-benchers, who sit on the first of the long benches in the House of Commons, are members of the Cabinet. Back-benchers are those who sit on any of the other benches; they are simply Members of Parliament and have no other position.
Emlyn Williams was offered a role.