Following Britain's reluctant declaration of war on Hitler's Nazi Germany, Conservative prime minister Neville Chamberlain takes emergency measures and brings political rival Winston Churchill back into the cabinet.
But Chamberlain's failure to halt Germany's invasion of Norway and Denmark in 1940 force him to resign. Labour plays a key part in ensuring he steps down. His unlikely successor is Churchill after foreign secretary Lord Halifax rules himself out. With Churchill at the helm, Labour leader Clement Attlee is installed as his effective and businesslike deputy.
With support for social reform and the determination to build a better society from the ashes of war gaining public support, particularly after the publication of the Beveridge report in 1942, Labour quits the wartime coalition immediately victory in Europe is declared in 1945.
The party's stock with the voters has risen during war, but by just how much surprises everyone. None more so than Churchill, who finds himself dumped by the voters despite his war record.