ONS coding system

The Office for National Statistics coding system is a hierarchical code used in the United Kingdom for tabulating census and other statistical data.

Authorities, wards, and census areas
The code is constructed top down from a 4 character code representing a unitary authority or administrative county & district, eg:

Local Government wards have a two-letter code within their local authority, and Census Output Areas an additional 4 digits within a ward. Census Output Areas (OAs) are the smallest unit for which census data is published - they contain at least 40 households (preferably 100), and are built up from postcode blocks after the census data is available, with a view to being socially as homogeneous as possible. A new set of Output Areas will be created for each decennial census. Census 2001 was the first to use this system - previously census data was published for larger Enumeration Districts which were delineated before the census was conducted. Enumeration Districts are still used for the collection of data but not for publication.

The authority and ward codes are recognised by Eurostat as Local administrative unit code levels 1 & 2 within the NUTS system.

Civil parishes
An overlapping system encodes Civil Parish areas. Parishes are represented by an additional 3 digits within their local authority:

Super Output Areas
Super Output Areas (SOAs) are a set of geographies developed after the 2001 census. The aim was to produce a set of areas of consistent size, whose boundaries would not change (unlike electoral wards). They are an aggregation of adjacent Output Areas with similar social characteristics. Lower Layer SOAs typically contain 4 to 6 OAs with a population of around 1500. Middle Layer SOAs on average have a population of 7,200. Upper Layer SOAs are still being calculated; they are expected to cover a population of at least 25,000 each.

ONS codes for counties & districts
Also showing NUTS(3) codes thus:

Single-tier districts

 * London
 * City of London
 * Barking and Dagenham
 * Barnet
 * Bexley
 * Brent
 * Bromley
 * Camden
 * Croydon
 * Ealing
 * Enfield
 * Greenwich
 * Hackney
 * Hammersmith and Fulham
 * Haringey
 * Harrow
 * Havering
 * Hillingdon
 * Hounslow
 * Islington
 * Kensington and Chelsea
 * Kingston upon Thames
 * Lambeth
 * Lewisham
 * Merton
 * Newham
 * Redbridge
 * Richmond upon Thames
 * Southwark
 * Sutton
 * Tower Hamlets
 * Waltham Forest
 * Wandsworth
 * Westminster
 * Greater Manchester districts
 * Bolton
 * Bury
 * Manchester
 * Oldham
 * Rochdale
 * Salford
 * Stockport
 * Tameside
 * Trafford
 * Wigan
 * Merseyside districts
 * Knowsley
 * Liverpool
 * St Helens
 * Sefton
 * Wirral
 * South Yorkshire districts
 * Barnsley
 * Doncaster
 * Rotherham
 * Sheffield
 * Tyne and Wear districts
 * Gateshead
 * Newcastle-upon-Tyne
 * North Tyneside
 * South Tyneside
 * Sunderland
 * West Midlands districts
 * Birmingham
 * Coventry
 * Dudley
 * Sandwell
 * Solihull
 * Walsall
 * Wolverhampton
 * West Yorkshire districts
 * Bradford
 * Calderdale
 * Kirklees
 * Leeds
 * Wakefield
 * Unitary authorities - North East England region
 * Hartlepool
 * Middlesbrough
 * Redcar and Cleveland
 * Stockton-on-Tees
 * Darlington
 * Unitary authorities - North West England region
 * Halton
 * Warrington
 * Blackburn with Darwen
 * Blackpool
 * Unitary authorities - Yorkshire and the Humber region
 * Kingston upon Hull
 * East Riding of Yorkshire
 * North East Lincolnshire
 * North Lincolnshire
 * York
 * Unitary authorities - East Midlands region
 * Derby
 * Leicester
 * Rutland
 * Nottingham
 * Unitary authorities - West Midlands region
 * Herefordshire
 * Telford and Wrekin
 * Stoke-on-Trent
 * Unitary authorities - South West England region
 * Bath and North East Somerset
 * Bristol
 * North Somerset
 * South Gloucestershire
 * Plymouth
 * Torbay
 * Bournemouth
 * Poole
 * Swindon
 * Unitary authorities - East of England region
 * Peterborough
 * Luton
 * Southend-on-Sea
 * Thurrock
 * Unitary authorities - South East England region
 * Medway
 * Bracknell Forest
 * West Berkshire
 * Reading
 * Slough
 * Windsor and Maidenhead
 * Wokingham
 * Milton Keynes
 * Brighton and Hove
 * Portsmouth
 * Southampton
 * Isle of Wight
 * Welsh authorities
 * Isle of Anglesey
 * Gwynedd
 * Conwy
 * Denbighshire
 * Flintshire
 * Wrexham
 * Powys
 * Ceredigion
 * Pembrokeshire
 * Carmarthenshire
 * Swansea
 * Neath Port Talbot
 * Bridgend
 * Vale of Glamorgan
 * Rhondda Cynon Taff
 * Merthyr Tydfil
 * Caerphilly
 * Blaenau Gwent
 * Torfaen
 * Monmouthshire
 * Newport
 * Cardiff
 * Scottish districts
 * Aberdeen
 * Aberdeenshire
 * Angus
 * Argyll and Bute
 * Scottish Borders
 * Clackmannanshire
 * West Dunbartonshire
 * Dumfries and Galloway
 * Dundee
 * East Ayrshire
 * East Dunbartonshire
 * East Lothian
 * East Renfrewshire
 * Edinburgh
 * Falkirk
 * Fife
 * Glasgow
 * Highland
 * Inverclyde
 * Midlothian
 * Moray
 * North Ayrshire
 * North Lanarkshire
 * Orkney Islands
 * Perth and Kinross
 * Renfrewshire
 * Shetland Islands
 * South Ayrshire
 * South Lanarkshire
 * Stirling
 * West Lothian
 * Eilean Siar (Western Isles)

Two-tier counties & districts

 * obsolete, were Greater London & the metropolitan counties
 * obsolete, was Avon
 * obsolete, was Bath
 * obsolete, was Bristol
 * obsolete, was Kingswood
 * obsolete, was Northavon
 * obsolete, was Wansdyke
 * obsolete, was Woodspring
 * Bedfordshire
 * obsolete, was Luton
 * Mid Bedfordshire
 * Bedford
 * South Bedfordshire
 * obsolete, was Berkshire
 * obsolete, was Bracknell Forest
 * obsolete, was Newbury
 * obsolete, was Reading
 * obsolete, was Slough
 * obsolete, was Windsor and Maidenhead
 * obsolete, was Wokingham
 * Buckinghamshire
 * Aylesbury Vale
 * Chiltern
 * obsolete, was Milton Keynes
 * South Bucks
 * Wycombe
 * Cambridgeshire
 * Cambridge
 * East Cambridgeshire
 * Fenland
 * Huntingdonshire
 * obsolete, was Peterborough
 * South Cambridgeshire
 * Cheshire
 * Chester
 * Congleton
 * Crewe and Nantwich
 * Ellesmere Port and Neston
 * obsolete, was Halton
 * Macclesfield
 * Vale Royal
 * obsolete, was Warrington
 * obsolete, was Cleveland
 * obsolete, was Hartlepool
 * obsolete, was Langbaurgh-on-Tees
 * obsolete, was Middlesbrough
 * obsolete, was Stockton-on-Tees
 * Cornwall and Scilly
 * Caradon
 * Carrick
 * Kerrier
 * North Cornwall
 * Penwith
 * Restormel
 * Isles of Scilly
 * Cumbria
 * Allerdale
 * Barrow-in-Furness
 * Carlisle
 * Copeland
 * Eden
 * South Lakeland
 * Derbyshire
 * Amber Valley
 * Bolsover
 * Chesterfield
 * obsolete, was Derby
 * Derbyshire Dales
 * Erewash
 * High Peak
 * North East Derbyshire
 * South Derbyshire
 * Devon
 * East Devon
 * Exeter
 * Mid Devon
 * North Devon
 * obsolete, was Plymouth
 * South Hams
 * Teignbridge
 * obsolete, was Torbay
 * Torridge
 * West Devon
 * Dorset
 * obsolete, was Bournemouth
 * Christchurch
 * East Dorset
 * North Dorset
 * obsolete, was Poole
 * Purbeck
 * West Dorset
 * Weymouth and Portland
 * County Durham
 * Chester-le-Street
 * obsolete, was Darlington
 * Derwentside
 * Durham
 * Easington
 * Sedgefield
 * Teesdale
 * Wear Valley
 * East Sussex
 * obsolete, was Brighton
 * Eastbourne
 * Hastings
 * obsolete, was Hove
 * Lewes
 * Rother
 * Wealden
 * Essex
 * Basildon
 * Braintree
 * Brentwood
 * Castle Point
 * Chelmsford
 * Colchester
 * Epping Forest
 * Harlow
 * Maldon
 * Rochford
 * obsolete, was Southend-on-Sea
 * Tendring
 * obsolete, was Thurrock
 * Uttlesford
 * Gloucestershire
 * Cheltenham
 * Cotswold
 * Forest of Dean
 * Gloucester
 * Stroud
 * Tewkesbury
 * Hampshire
 * Basingstoke and Deane
 * East Hampshire
 * Eastleigh
 * Fareham
 * Gosport
 * Hart
 * Havant
 * New Forest
 * obsolete, was Portsmouth
 * Rushmoor
 * obsolete, was Southampton
 * Test Valley
 * Winchester
 * obsolete, was Hereford and Worcester
 * obsolete, was Bromsgrove
 * obsolete, was Hereford
 * obsolete, was Leominster
 * obsolete, was Malvern Hills
 * obsolete, was Redditch
 * obsolete, was South Herefordshire
 * obsolete, was Worcester
 * obsolete, was Wyre Forest
 * obsolete, was Wychavon
 * Hertfordshire
 * Broxbourne
 * Dacorum
 * East Hertfordshire
 * Hertsmere
 * North Hertfordshire
 * St Albans
 * Stevenage
 * Three Rivers
 * Watford
 * Welwyn Hatfield
 * obsolete, was Humberside
 * obsolete, was Boothferry
 * obsolete, was Cleethorpes
 * obsolete, was East Yorkshire
 * obsolete, was Beverley
 * obsolete, was Glanford
 * obsolete, was Holderness
 * obsolete, was Great Grimsby
 * obsolete, was Kingston upon Hull
 * obsolete, was Scunthorpe
 * obsolete, was Isle of Wight county
 * obsolete, was Medina
 * obsolete, was South Wight
 * Kent
 * Ashford
 * Canterbury
 * Dartford
 * Dover
 * obsolete, was Gillingham
 * Gravesham
 * Maidstone
 * obsolete, was Rochester upon Medway
 * Sevenoaks
 * Shepway
 * Swale
 * Thanet
 * Tonbridge and Malling
 * Tunbridge Wells
 * Lancashire
 * obsolete, was Blackburn
 * obsolete, was Blackpool
 * Burnley
 * Chorley
 * Fylde
 * Hyndburn
 * Lancaster
 * Pendle
 * Preston
 * Ribble Valley
 * Rossendale
 * South Ribble
 * West Lancashire
 * Wyre
 * Leicestershire
 * Blaby
 * Charnwood
 * Harborough
 * Hinckley and Bosworth
 * obsolete, was Leicester
 * Melton
 * North West Leicestershire
 * Oadby and Wigston
 * obsolete, was Rutland
 * Lincolnshire
 * Boston
 * East Lindsey
 * Lincoln
 * North Kesteven
 * South Holland
 * South Kesteven
 * West Lindsey
 * Norfolk
 * Breckland
 * Broadland
 * Great Yarmouth
 * King's Lynn and West Norfolk
 * North Norfolk
 * Norwich
 * South Norfolk
 * Northamptonshire
 * Corby
 * Daventry
 * East Northamptonshire
 * Kettering
 * Northampton
 * South Northamptonshire
 * Wellingborough
 * Northumberland
 * Alnwick
 * Berwick-upon-Tweed
 * Blyth Valley
 * Castle Morpeth
 * Tynedale
 * Wansbeck
 * North Yorkshire
 * Craven
 * Hambleton
 * Harrogate
 * Richmondshire
 * Ryedale
 * Scarborough
 * Selby
 * obsolete, was York
 * Nottinghamshire
 * Ashfield
 * Bassetlaw
 * Broxtowe
 * Gedling
 * Mansfield
 * Newark and Sherwood
 * obsolete, was Nottingham
 * Rushcliffe
 * Oxfordshire
 * Cherwell
 * Oxford
 * South Oxfordshire
 * Vale of White Horse
 * West Oxfordshire
 * Shropshire
 * Bridgnorth
 * North Shropshire
 * Oswestry
 * Shrewsbury and Atcham
 * South Shropshire
 * obsolete, was The Wrekin
 * Somerset
 * Mendip
 * Sedgemoor
 * South Somerset
 * Taunton Deane
 * West Somerset
 * Staffordshire
 * Cannock Chase
 * East Staffordshire
 * Lichfield
 * Newcastle-under-Lyme
 * South Staffordshire
 * Stafford
 * Staffordshire Moorlands
 * obsolete, was Stoke-on-Trent
 * Tamworth
 * Suffolk
 * Babergh
 * Forest Heath
 * Ipswich
 * Mid Suffolk
 * St. Edmundsbury
 * Suffolk Coastal
 * Waveney
 * Surrey
 * Elmbridge
 * Epsom and Ewell
 * Guildford
 * Mole Valley
 * Reigate and Banstead
 * Runnymede
 * Spelthorne
 * Surrey Heath
 * Tandridge
 * Waverley
 * Woking
 * Warwickshire
 * North Warwickshire
 * Nuneaton and Bedworth
 * Rugby
 * Stratford-on-Avon
 * Warwick
 * West Sussex
 * Adur
 * Arun
 * Chichester
 * Crawley
 * Horsham
 * Mid Sussex
 * Worthing
 * Wiltshire
 * Kennet
 * North Wiltshire
 * Salisbury
 * obsolete, was Thamesdown
 * West Wiltshire
 * Worcestershire
 * Bromsgrove
 * Malvern Hills
 * Redditch
 * Worcester
 * Wychavon
 * Wyre Forest

Northern Ireland districts

 * Derry
 * Limavady
 * Coleraine
 * Ballymoney
 * Moyle
 * Larne
 * Ballymena
 * Magherafelt
 * Cookstown
 * Strabane
 * Omagh
 * Fermanagh
 * Dungannon and South Tyrone
 * Craigavon
 * Armagh
 * Newry and Mourne
 * Banbridge
 * Down
 * Lisburn
 * Antrim
 * Newtownabbey
 * Carrickfergus
 * North Down
 * Ards
 * Castlereagh
 * Belfast

Non-hierarchical codes for summary data in metropolitan areas

 * Inner London
 * Outer London
 * Greater Manchester
 * Merseyside
 * South Yorkshire
 * Tyne and Wear
 * West Midlands
 * West Yorkshire

2009 structural changes
The following changes will be made on 1st April 2009 to reflect the 2009 structural changes to local government in England.