Twelve regional electricity companies were sold together in 1990
The Electricity Act 1947 set up twelve Area Boards to supply electricity to homes and businesses across England and Wales. Under the Electricity Act 1989, each board's business passed on 31 March 1990 to a successor company: the twelve regional electricity companies. In December 1990 the government offered shares in all twelve at once. The offer was more than ten times subscribed, with 12.75 million applications, and raised £7,713m. Each answer is the company's 1990 name; the old board's name and the abbreviations used in official documents also count. The list is fixed.
Name them all first. Then try the harder part: name them region by region, from London and the south-east to the north of England.