I'd like to thank everyone for their suggestions and advice on how to improve this TL and make it more plausible (I especially like the idea surrounding Walter Elliot). One question, though - would a change in Labour's leadership (i.e. someone in charge other than Attlee) help Churchill win in 1945?
The main contenders would seem to be:
Hugh Dalton, who would be more likely to make errors after a victory than give any particular boost to the Tories during the election. Dalton was known to have been a strong opponent of Appeasement, and was keen to ensure the social reforms happened.
Ernest Bevin, who would probably give a swing to Labour. He was popular with the Americans, and he was Minister of Labour during the war, with a remarkable record of success.
Attlee was not especially charismatic, and indeed was "notoriously laconic".
One thing that will help is a total re-jig of the Tory campaign. In OTL, it was essentially entirely "Churchill is wonderful", and the voters remembered what Churchill was like during the Depression. It wasn't helped by Churchill's comments during the campaign. In one radio broadcast, he said that a Labour government would introduce a form of gestapo to implement the reforms. That backfired. Gagging Churchill during the campaign could probably swing half a point to the Tories.
To win elections, you've got to judge the public mood. In 1945, the public wanted the men home, not off fighting pointless little colonial wars to hang on to Empire that did no good to anyone who was just an ordinary working bloke. The public wanted their "Land fit for Heroes", where you didn't have the inequalities of the Depression. They wanted homes and jobs and an end to going hungry to make ends meet, while the rich ignore the problems. The ordinary voter didn't care who ruled India.