UK GSS code
The nine-character code identifying a UK administrative or statistical area in the coding system kept by the Office for National Statistics.
The Government Statistical Service coding system replaced the older ONS codes in January 2011. The Office for National Statistics maintains the register and a code history database that records every change since 2009.
Nine characters in two parts. The first three are the entity: a country letter, E England, W Wales, S Scotland, N Northern Ireland, or K for units spanning the whole United Kingdom, followed by two digits for the kind of area. The remaining six are a sequential number within that entity. Common entities are E06 unitary authority, E07 non-metropolitan district, E08 metropolitan district, E09 London borough, E10 shire county, W06 and S12 the Welsh and Scottish council areas.
The codes are deliberately not hierarchical. The Office states that a lower-tier code bears no relation to the code of its parent, so a county cannot be derived from a district code by truncation the way it can in Germany or Spain. The six-digit number is unique only inside its entity: E06000001 and E07000001 are unrelated places.
A boundary change retires a code and issues a new one rather than editing the old. Northumberland was E06000048 until 2013 and has been E06000057 since. Codes are not reused, so a code identifies an area as it stood at a point in time, and a value from an older dataset may no longer resolve.
