I'm wondering what would have happened had Britain gone to the polls one more time right before the start of WW 2, either due to an election held right before the start of the war, or had the war been delayed a year, so a potential 1940 election. Based on the numerous byelections held, it seems likely that the Conservatives would have won but with a much reduced majority.
Also of interest would have been whether Tory rebels would have been renominated by their associations, or whether Chamberlain would have tried for a party purge.