Spot on Rob. During the war (omigod I'm sounding like Littledick now doing one of his 'hilarious' pisstakes), the home front was pretty much run by Labour politicos (Attlee, Bevan, Bevin, Beveridge etc), while the foreign office, media and armed forces were run by Conservatives, such as Eden, Beaverbrook etc. Probably because those Tories were better at smooth-talking to the USA, had a better relationship with the military high command and so on. But the generally good running of home affairs convinced many people that labour were not all 5th-column Bolshies, but actually quite competent.
Problem was, war is a catalyst for change. Britain in 1945 was radically different to Britain in 1939. And contrary to popular belief, the entire population did not spend those 6-ish years cowering in a tube station singing 'We'll meet again', cheering the Queen Mum, or shagging American squaddies. Life went on, prices rose and availability of goods became short. Come the end of the war, many people had a radically different worldview to what they had in 1939. Peace, stability and regrowth were the main things people wanted (especially returning military folk). Labour campaigned on a strong ticket of rebuilding, health and security for all, and the Tories, campaigning on a ticket of mostly 'LOOK, it's WINSTON BLOODY CHURCHILL!!!' couldn't really compete.
Aside from the fact that he had copious military experience, and had spotted the danger of letting the Nazis re-arm Germany (well done, 10 points), Churchill was a pretty useless peacetime politician. He was a great orator, sure, but so is George Galloway. He flipped between parties, had a tendancy to stomp off in a sulk if he didn't get his way, and had a reputation for ill-thought-out grandiose plans. Above all he was obsessed with securing his 'place in history'.
Remind you of anyone?
In war, especially when Britain was threatened gravely with invasion, occupation and possible annihalation, you do need a strong leader who is prepared to let some of the niceties of democracy go hang. However you sure as hell don't need them in peacetime. He and the Tories campaigned on a ticket of 'Yah boo, we won the war'. Attlee and Labour offered positive new ideas. And after 6 years of war, most people were heartily sick of the idea of glorification of war. Thus the landslide.
Ten seconds... the pain begins.
Fifteen seconds... you can't breathe.
Twenty seconds... you give up and turn off the Jeremy Vine show.