List of pre-nationalisation UK electric power companies

The board's area was defined as: Cambridgeshire, Hertfordshire, Huntingdonshire, the Isle of Ely, Norfolk, Suffolk and parts of Bedfordshire, Buckinghamshire, Essex, Middlesex, Oxfordshire and the Soke of Peterborough.

Created under the provisions of the Electricity (Supply) Act 1919 The board's area was defined as: Anglesey, Caernarvonshire, Denbighshire, Flintshire, Merionethshire, Montgomeryshire and parts of Cardiganshire, Cheshire, Lancashire (including Liverpool) and Shropshire.

Created under the provisions of the Electricity (Supply) Act 1919 The board's area was defined as: Herefordshire, Worcestershire and parts of Gloucestershire, Oxfordshire, Shropshire, Staffordshire and Warwickshire (including Birmingham).

Created under the provisions of the Electricity (Supply) Act 1919 The board's area was defined as: Brecknockshire, Carmarthenshire, Glamorganshire, Monmouthshire, Pembrokeshire, Radnorshire and part of Cardiganshire.

The board's area was defined as: Berkshire, Hampshire, the Isle of Wight, Wiltshire and parts of Buckinghamshire, Dorsetshire, Gloucestershire, Middlesex, Oxfordshire, Somersetshire, Surrey and Sussex.