How it started
Origins
The company has its origins in two public sector electricity supply authorities. The former North of Scotland Hydro-Electric Board was founded in 1943 to design, construct and manage hydroelectricity projects in the Highlands of Scotland, and took over further generation and distribution responsibilities on the nationalisation of the electricity industry within the United Kingdom in 1948.
The former Southern Electricity Board was created in 1948 to distribute electricity in Southern England. Whilst the Southern Electricity Board was a distribution only authority, with no power generation capacity of its own, the North of Scotland Hydro-Electric board was a broader spectrum organisation, with its own generating capabilities.
Because of its history and location, the Hydro-Electric Board was responsible for most of the hydroelectric generating capacity in the United Kingdom. Both authorities were privatised in 1990/91, initially retaining their pre privatisation geographic and functional bases. The North of Scotland Hydro-Electric Board became Scottish Hydro-Electric, whilst the Southern Electricity Board became Southern Electric. They both later became part of Scottish and Southern Electricity Networks (SSEN) - Distribution.
Post privatisation
Scottish and Southern Energy was formed in September 1998, following a merger between Scottish Hydro-Electric and Southern Electric. In August 2000, Scottish and Southern Energy acquired the SWALEC energy supply business. SWALEC operate exclusively in Wales while SSE operates in Scotland and England.
From Wikipedia’s article on SSE plc, shared under CC BY-SA 4.0.2