During the First World War, the demand for industrial electricity increased. This tested the capacity of existing suppliers and exposed their lack of co-ordination. In 1919, the government appointed Electricity Commissioners to encourage undertakings to adopt common technical standards and co-ordinate production on a regional basis. From the late 1920s, the Commission worked with the Central Electricity Board to develop the National Grid (see below). The Commission was limited because it had no compulsory powers, but its Annual Returns and Returns of Engineering and Finance provide detailed information about the extent and structure of the industry.