In 1945 Labor was certainly better organized and had a coherent playbook. The Conservatives had in one way or another been in power since 1930 and had become distracted with personal issues, including an unspoken cleavage between the Churchill-national party types and many back benchers who dislikes and distrusted Churchill and only stuck to him as a national figure. These people intensely disliked the national party interventionist foreign policy and blamed Churchill for the impending destruction of the Empire and the financial bankruptcy of GB. They never believed going to war with Germany was anything but a guarantee of the end of British power. The Conservatives had been losing by elections steadily for four years. Because Britain is a parliamentry government that means elections are local but are the voice of the voter on national parties. These loses telegraphed a deep shift in public opinion the divided Conservative Party did nothing to investigate and develop a coping strategy for. Why the Conservatives were so optimistic in going into the election is that the party took the easy and lazy way out and equated Churchill with Victory in the greatest war in history which would equate overwhelming voter gratitude at the ballot box.
But Churchill and the Tories were back in 1950, when Brits realized that Labour couldn’t deliver on the promises of Socialism.