The London Electricity Board. | The administrative County of London and parts of Essex, Kent, Middlesex and Surrey. |
The South Eastern Electricity Board. | Parts of Kent, Middlesex, Surrey and Sussex. |
The Southern Electricity Board. | Berkshire, Hampshire, the Isle of Wight, Wiltshire and parts of Buckinghamshire, Dorsetshire, Gloucestershire, Middlesex, Oxfordshire, Somersetshire, Surrey and Sussex. |
The South Western Electricity Board. | Cornwall (including the Isles of Scilly), Devonshire and parts of Dorsetshire, Gloucestershire (including Bristol) and Somersetshire. |
The Eastern Electricity Board. | Cambridgeshire, Hertfordshire, Huntingdonshire, the Isle of Ely, Norfolk, Suffolk and parts of Bedfordshire, Buckinghamshire, Essex, Middlesex, Oxfordshire and the Soke of Peterborough. |
The East Midlands Electricity Board. | Leicestershire, Northamptonshire, Rutland and parts of Bedfordshire, Buckinghamshire, Derbyshire, Lincolnshire, Nottinghamshire, the Soke of Peterborough, Staffordshire and Warwickshire. |
The Midlands Electricity Board. | Herefordshire, Worcestershire and parts of Gloucestershire, Oxfordshire, Shropshire, Staffordshire and Warwickshire (including Birmingham). |
The South Wales Electricity Board. | Brecknockshire, Carmarthenshire, Glamorganshire, Monmouthshire, Pembrokeshire, Radnorshire and part of Cardiganshire. |
The Merseyside & North Wales Electricity Board. | Anglesey, Caernarvonshire, Denbighshire, Flintshire, Merionethshire, Montgomeryshire and parts of Cardiganshire, Cheshire, Lancashire (including Liverpool) and Shropshire. |
The Yorkshire Electricity Board. | Parts of Derbyshire, Lincolnshire, Nottinghamshire and of the East and West Ridings of Yorkshire. |
The North Eastern Electricity Board. | Durham, Northumberland, the North Riding of Yorkshire and parts of the East and West Ridings of Yorkshire (including York). |
The North Western Electricity Board. | Cumberland, Westmorland and parts of Cheshire, Derbyshire, Lancashire (including Manchester) and of the West Riding of Yorkshire. |
The South East Scotland Electricity Board. | Berwickshire, Clackmannanshire, Fifeshire, Lothians, Peebles, Selkirkshire and parts of Dunbartonshire, Roxburghshire and Stirlingshire. |
The South West Scotland Electricity Board. | Ayrshire, Dumfries-shire, Kirkcudbrightshire, Lanarkshire, Renfrewshire, Wigtownshire and parts of Dunbartonshire, Roxburghshire and Stirlingshire. |