I think the most likely outcome of an election in 1939 is actually a tory victory. But maybe it happens just at the time when the occupaiton of Prage exposes the disaster of appeasment.
I presume Attlee would have declaared war at the same time.
Queary after Dunkirk are tories and liberals offered cabinet seats?
How big of a difference does it make to India?
What is the result of the 1945 election?
How much, if any, role does Churchill play