The electricity industry developed from the nineteenth century as a patchwork of local municipal and private sector electricity providers. By 1921 over 480 undertakers had been authorised to supply electricity in England and Wales. In 1926 the Government intervened and established the Central Electricity Board to build and manage a nationwide high voltage transmission system, both to increase coverage and ensure more security of supply. In 1948 the industry was nationalised and the third of electricity suppliers that were privately owned were taken into public ownership. The British Electricity Authority was established, responsible for electricity generation and high voltage transmission, alongside 12 regional Area Boards in England and Wales and two in Scotland. In 1955 the British Electricity Authority became the Central Electricity Authority and in 1957 the Central Electricity Generating Board (CEGB).