British war films with 'Canadians'

Why do so many British Second World War films feature the lead as a 'Canadian'?

Well, of course, I think we all know the answer!

Films shot during the war, but prior to the Americans joining in (late) needed to feature an American hero for one of two reasons:

- they wanted to encourage America to join the allies;

- they were paid for or subsidised by American film companies.

As America had not joined in yet, the best they could do without appearing too historically inaccurate would be to include an American who joined the Canadian forces!