Finished the book. Excellent read. Paints a fascinating picture of British politics of the era. England was run by an old boy network elite. These guys were alumni of the same few schools, partied together, married each other, and owned all the important businesses. Parliament was operated by the Tory party which had total control over who could run for parliament, who got a prestigious position, who became prime minister. All done by word of mouth and tradition, nothing formalized in writing. Tory MP's found it impossible to vote against any government bills. Even if they deeply disapproved, the furthest they could go was to abstain from the vote. Voting against a measure of your party was simply never done. American visitors and reporters had difficulty understanding this.
The end came for Neville Chamberlain over the Norway disaster in the spring of 1940. After some vigorous Chamberlain bashing on the floor of Commons, Chamberlain made the next vote a vote of confidence in him. After the votes were counted, Chamberlain had won, but by a narrow margin of merely 80 odd votes, when the Tories had 400 and something seats in Commons. The narrowness of the margin was adjudged a defeat, and Churchill became Prime Minister.