In the years after the First World War the British government had to adapt its communication policy to connect with the new mass electorate. This book examines the government's own Film Units and their slow development of the Public Information Film. By reviewing the entire film catalogue produced by the Empire Marketing Board, the General Post Office and Crown Film Units, particular themes are identified which not only reflect the demands of the Units' sponsors but also the anxieties and concerns of the 1930s and 1940s. The impact of the films is explored through the contemporary reaction of the audiences to them. By the time the Crown Film Unit was closed in 1952 a style of Public information film had been developed and continued into the 1970s.