The post-war electoral competition took place within a new framework. The franchise had been extended. Constituency boundaries had been redrawn. While franchise extension did not substantially alter the electoral framework in Labour's favour, boundary revision did. It created more seats with a high concentration of working-class voters, and proportionally more mining constituencies. These were the seats which Labour was most likely to win (Section I). Despite this, structural changes alone cannot explain Labour's development. Within the labour elite, support for an increased commitment to Labour politics before 1917 was partial. Statist groups displayed increased interest (Section II), but a more general increase in support was not evident before the last stage of the war. Arthur Henderson sought to break out of the Progressive Alliance (Section III) not because of changes in union opinion or improvements in constituency organisation but because of new political circumstances (Section IV). Even by 1918, Labour organisation was weak in most of the formerly Liberal working-class areas because it had not ‘solved’ its old problems. Similarly, it had made organisational progress only in parts of the mining and Tory areas where before 1914 it seemed to have more potential than the Liberals as an anti-Tory force. Statist policies, and Statist unions, were not strong enough to create substantial organisations even in areas where Labour had a comparative advantage. Henderson had to canvass non-Statist unions and persuade them to finance more parliamentary candidates.