Stuart Ball 
The Conservative Party and British Politics 1902 – 1951 [PDF ebook] 

The history of the Conservative Party during the first half of the twentieth century was marked by crisis and controversy, from Joseph Chamberlain“s tariff reform campaign through the Lloyd George coalition and the National Government between the wars to the defeat of 1945 and the post war recovery. This study provides a lucid account of this turbulent and formative period in the history of the most durable and adaptive force in modern British politics.