The possibility to consider is - what would happen if Edward called Stanley Baldwin's bluff regarding the threat that, should he insist on marrying Wallis, the government would resign.
Edward had offered to enter a morganatic marriage, but the government had turned this offer down.
But if Baldwin caused the government to resign, then Edward would have had to offer government to Attlee several years earlier than he would have formed it. And given Attlee was anti-appeasement, the Phony War may never have escalated further. As such, Halifax would never have been in position to become PM.
Unless Baldwin had the government resign, Attlee refused to form one and Edward then had to force through a General Election which Chamberlain might win, leading to a subsequent Halifax/Churchill leadership challenge.