You might be interested in past post on the same topic from the FAQ section on Churchill:

• How, given the popularity of Churchill, was the UK Labour party able to obtain such a decisive victory in the 1945 election?
  ^(06 Jun 2015 | 7 comments)
  ^(/u/mevidek describes how Churchill's actions both pre-war and during it affected his election chances towards the end of WWII as well how Labour gained public during the same time.)