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

It was replaced by the GSS coding system on 1 January 2011.

Code formulation

Principal authorities

The code was constructed top down from a four character code representing a unitary authority or two-tier county and district.

or
00ECMiddlesbrough (unitary)
12Cambridgeshire county
12UBCambridge district

Electoral wards and output areas

Local government wards had a two-letter code within their local authority, and census output area an additional four digits within a ward.

12UBCambridge district
12UBGAPetersfield ward
12UBGA0001Output area: Gwydir Street (north of junction with Hooper St)

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

Civil parishes

An overlapping system encoded civil parish areas. Parishes were represented by an additional three digits within their local authority:

12UDFenland district
12UD010Tydd St. Giles parish

List of codes for counties and districts

The codes for counties and districts were as follows.

Also showing NUTS(3) codes thus: (UKH12)

Greater London

These codes became active following local government changes in 1986.

Metropolitan counties

These codes became active following local government changes in 1986.

Non-hierarchical codes for Greater London and metropolitan counties

Unitary authorities established in the 1990s

These codes became active following local government changes the 1990s.

Unitary authorities established in 2009

These codes became active following local government changes in 2009.

  • 00KB Bedford
  • 00KC Central Bedfordshire
  • 00EQ Cheshire East
  • 00EW Cheshire West and Chester
  • 00HE Cornwall
  • 00HF Isles of Scilly
  • 00EJ County Durham
  • 00EM Northumberland
  • 00GG Shropshire
  • 00HY Wiltshire

Non-metropolitan counties

Wales

These codes became active following local government changes in 1996.

Scotland

These codes became active following local government changes in 1996.

Northern Ireland

External links