The history of the first National Grid for electricity supply encompasses technical, economic, commercial, political, environmental and other aspects of history. This paper, published on the sixtieth anniversary of the building of the first Grid, reviews the concept, system technology, construction, and early operation. The period covered includes the engineering concept and preparatory phase (1916–1926), the construction phase (1927–1933), and the early development and management (1933–1948), including the interwar peacetime and wartime (1939–1945). The Central Electricity Board (1927–1948), the builder and owner of the Grid and controller of the selected power stations, is considered in the context of the organisation of electricity supply.