Ask what county Edinburgh is in and you can get three answers. The council is the City of Edinburgh. The Lord-Lieutenant represents the City of Edinburgh too. The historic county is Midlothian, and some Edinburgh residents will tell you so. None of them is wrong, because the UK runs three county systems at once, and the address on an envelope does not say which one it means.

Geocodio's gazetteer append returns all three for any UK address, postcode, or coordinate pair: county.ceremonial, county.historic, and the administrative tier as authority.local and authority.regional, each with the agency that publishes it and, for the administrative tier, the official GSS code.

Why does the UK have three kinds of county?

Counties started as units of government and stayed as units of identity after the government moved on. The 1974 local government reforms in England and Wales (1975 in Scotland) redrew the administrative map, created new counties like Greater Manchester and Avon, and in places abolished names that had been in use for a thousand years. Later reforms undid some of that: Avon, Cleveland, and Humberside were split into unitary authorities in 1996, and Cumbria County Council was abolished in 2023. Through all of it, the counties people identify with changed far less than the ones that collected the rates.

The result is three overlapping systems.

What do the three systems look like for real addresses?

Every value below is a live Geocodio response.

A few things stand out:

• Winchester is the easy case. Hampshire is a two-tier county, so Hampshire County Council is the regional authority, and Hampshire is also both the ceremonial and the historic county. The three systems agree.

• The big cities are where they diverge. Manchester has been a metropolitan district of Greater Manchester since 1974, but its historic county is Lancashire. Westminster is in Greater London today and Middlesex historically. Middlesex has had no council since 1965 and no Lord-Lieutenant either, and still appears on letterheads, cricket scorecards, and in county.historic.

• Scotland and Wales use their own ceremonial names. The City of Edinburgh is a lieutenancy area. South Glamorgan is a preserved county, kept for ceremonial purposes after the Welsh counties were replaced by unitary authorities in 1996. Welsh councils also carry their Welsh name: Cardiff's authority.local has names of { "en": "Cardiff", "cy": "Caerdydd" }, while the ceremonial and historic counties are published in English only.

• Cumbria shows how the systems move at different speeds. Cumbria County Council was abolished in 2023 and replaced by two unitary authorities, so authority.regional is null and authority.local is Westmorland and Furness. Cumbria remains the ceremonial county, and Westmorland, the historic county that gave the new authority half its name, is what county.historic returns.

• The county council slot is only ever filled in England. Scotland, Wales, Northern Ireland, London, and every unitary and metropolitan area have a single tier, so authority.regional is null there.

Which county should I use?

It depends on what the column is for, and Geocodio returns all three so you do not have to pick in advance.

• Joining to government data or routing by council: use authority.local and its gss_code. Almost every UK dataset published by local authority area, from council tax bands to planning statistics, keys on this code. The UK census geographies append returns the same code alongside the smaller statistical areas.

• A human-readable "County" column: use county.ceremonial. It covers every UK address, matches what most people and most maps mean by county today, and changes rarely.

• Heritage, family history, sport, or anything that predates 1974: use county.historic.

• Mailing: none of them. Royal Mail stopped requiring a county on addresses in the 1990s, and the post town plus postcode is all a letter needs.

How is a postal county different?

It is not any of the three. Until the mid-1990s Royal Mail published a postal county for each post town, chosen to help sorting rather than to reflect any boundary, and many address databases still carry those values. Royal Mail no longer maintains them, so a postal county in an old address list may name a county that no longer exists in any system. Replacing it with county.ceremonial from the gazetteer is a straightforward clean-up.

How do I get the counties for my addresses?

Add gazetteer to the fields parameter on a geocode or reverse geocode request in API v2.

curl "https://api.geocod.io/v2/geocode?q=1+Princes+Street,+Edinburgh+EH2+2EQ&country=GB&fields=gazetteer&api_key=YOUR_API_KEY"

{
  "gazetteer": {
    "geographic_town": {
      "name": "Edinburgh",
      "names": { "en": "Edinburgh" },
      "type": "built_up_area",
      "code": { "gss_code": "S45001942" },
      "source": "Ordnance Survey"
    },
    "county": {
      "ceremonial": { "name": "City of Edinburgh", "names": { "en": "City of Edinburgh" }, "source": "Ordnance Survey" },
      "historic": { "name": "Midlothian", "names": { "en": "Midlothian" }, "source": "Historic Counties Trust" }
    },
    "authority": {
      "local": {
        "name": "City of Edinburgh",
        "names": { "en": "City of Edinburgh" },
        "type": "council_area",
        "code": { "gss_code": "S12000036" },
        "source": "Office for National Statistics"
      },
      "regional": null
    },
    "identifiers": {
      "uprn": { "value": "906203376", "source": "Ordnance Survey" },
      "usrn": { "value": "7903151", "source": "Ordnance Survey" }
    }
  }
}

The counties come with the rest of the gazetteer append: the town, the local authority with its GSS code, and the UPRN and USRN for rooftop matches. The append costs 1 credit per address on top of the geocoding lookup. Spreadsheet upload support is being released separately from the API.

Attribution

Ceremonial counties from Ordnance Survey and the Office for National Statistics codes are published under the Open Government Licence v3.0. The Historic Counties Trust asks to be credited when its data is used. The source on each value tells you who to name.