The Prime Minister Neville Chamberlain had been severely criticised in the Norway Debate and only won the vote because many Conservative MPs had abstained. Churchill had ended his speech in the Norway Debate with the words:
…let pre-war feuds die; let personal quarrels be forgotten, and let us keep our hatreds for the common enemy. Let party interest be ignored, let all our energies be harnessed, let the whole ability and forces of the nation be hurled into the struggle, and let all the strong horses be pulling on the collar.
Chamberlain concluded that he would have to resign, even though he had won the vote. He recognised the need allow a new Prime Minister to form a National Government, in which all the political Parties would be represented.
The Foreign Secretary, Lord Halifax was a strong contender but he ruled himself out because he sat in the Lords and it would be difficult to lead the Commons from there. He probably recognised that he was himself too closely associated with Chamberlain’s policies. The Labour Party leadership informed Chamberlain that they were only prepared to serve under Churchill, and Chamberlain was obliged to advise the King accordingly.
It was a popular choice in the country, where Churchill’s brilliant oratory resonated, but opinion was sharply divided amongst the political classes, where many thought him too much of a maverick to be a successful leader.