The events of the days of May, when Parliament replaced the “National” Government of the third Chamberlain by the “truly National” Government of the third Churchill, illustrate the danger of simple explanations of the working of the British constitution. The notion that responsible government could be expressed in terms of Parliamentary “control” of the Government in power has disappeared. There has been, however, a tendency to replace it by the equally naive explanation of Governmental control of Parliament. The truth lies in between. On the one hand, it must be recognized that, through the party machine, a Government with a majority has very substantial powers of control. On the other hand, it must equally be recognized that public opinion, acting through members of Parliament, has a profound influence on the policy of the Government. The precise relationship has never been fully investigated, because the British electoral machine has never been adequately studied. It is doubtful if it can ever be adequately expounded, because, like so many parts of the British constitution, it depends upon intangible elements which do not lend themselves easily to demonstration.