In Wales ‘Cardiff’ postcodes encompass several of the neighbouring local authorities, Vale of Glamorgan and Caerphilly for example both are covered by CF postcodes.
Yes, appreciate that CF covers a wide area, but do the lower level codes as shown in the Wiki link actually cross any county boundaries (eg in the Wikipedia list Caerphilly is CF83, and is correctly shown as mid-Glamorgan)?
That was my original point, the individual post codes do cross physical county lines. SP6 covers parts of physical Dorset and Hampshire, but that wikipedia link shows only Hampshire, as the postal county lines are different.
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Partly this is because postal addresses are entirely for the benefit of the post office and they therefore don’t necessarily update postal addresses when local authority boundaries change. I.e there parts of Farnborough, have Camberley, Surrey postal addresses. And then part of Fleet, Hart which still have Farnborough, Rushmoor addresses.
(Not that we are worried about Borough and District Councils in this context.)
Here’s N. Ireland postcode mapping. I note that a couple of towns do cross counties, however postcodes seem to fit firmly within one, assuming of course the table on Wikipedia is accurate.
| County | Postcodes |
|---|---|
| County Antrim | BT1, BT2, BT3, BT4, BT5, BT6, BT7, BT8, BT9, BT10, BT11, BT12, BT13, BT14, BT15, BT16, BT17, BT27, BT28, BT29, BT36, BT37, BT38, BT39, BT40, BT41, BT42, BT43, BT44, BT53, BT54, BT56, BT57, BT58 |
| County Armagh | BT35, BT60, BT61, BT62, BT63, BT64, BT65, BT66, BT67 |
| County Down | BT18, BT19, BT20, BT21, BT22, BT23, BT24, BT25, BT26, BT30, BT31, BT32, BT33, BT34 |
| County Fermanagh | BT74, BT92, BT93, BT94 |
| County Londonderry | BT45, BT46, BT47, BT48, BT49, BT51, BT52, BT55 |
| County Tyrone | BT68, BT69, BT70, BT71, BT75, BT76, BT77, BT78, BT79, BT80, BT81, BT82 |
As for Ireland, there’s a huge amount of breweries and places missing postcode data so I don’t think that will help things at all. A big help would be automatically putting any places/breweries in Dublin into County Dublin, as this will account for a fairly large amount. Some other major cities could probably be done this way too.
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This is potentially a useful website. I use it quite often at work when I am trying to identify the correct location for a building. Particuarly #1 on the contents table:
- Postcodes by administrative area
- A complete list of UK postcodes and their latitude/longitude
- Random postcode generator
- Measure distances between two points
- Lat/long finder - find the latitude and longitude of locations by clicking on a map
- Historical property sales data for England and Wales
- London postcodes - a complete list of London postcodes grouped by district
- Batch geocoding of UK postcodes
- Generate a bunch of random UK addresses
- Strava segment explorer
And here’s Wales. Note that NP7 is excluded as this covers parts of Gwent and Powys so these will need to be determined manually based on the full address.
| County | Postcodes |
|---|---|
| Gwent | NP4, NP10, NP11, NP12, NP13, NP15, NP16, NP18, NP19, NP20, NP22, NP23, NP24, NP25, NP26, NP44 |
| Dyfed | SA14, SA15, SA16, SA17, SA18, SA19, SA20, SA31, SA32, SA33, SA34, SA35, SA36, SA37, SA38, SA39, SA40, SA41, SA42, SA43, SA44, SA45, SA46, SA47, SA48, SA61, SA62, SA63, SA64, SA65, SA66, SA67, SA68, SA69, SA70, SA71, SA72, SA73, SY23, SY24, SY25 |
| Clwyd | CH5, CH6, CH7, CH8, LL11, LL12, LL13, LL14, LL15, LL16, LL17, LL18, LL19, LL20, LL21, LL22, LL28, LL29 |
| Gwynedd | LL23, LL24, LL25, LL26, LL27, LL23, LL30, LL31, LL32, LL33, LL34, LL35, LL36, LL37, LL38, LL39, LL40, LL41, LL42, LL43, LL44, LL45, LL46, LL47, LL48, LL49, LL51, LL52, LL53, LL54, LL55, LL56, LL57, LL58, LL59, LL60, LL61, LL62, LL63, LL64, LL65, LL66, LL67, LL68, LL69, LL70, LL71, LL72, LL73, LL74, LL75, LL76, LL77, LL78 |
| Powys | NP8, SY15, SY16, SY17, SY18, SY19, SY20, SY21, SY22 |
| Mid Glamorgan | CF31, CF32, CF33, CF34, CF35, CF36, CF37, CF38, CF39, CF40, CF41, CF42, CF43, CF44, CF45, CF46, CF47, CF48, CF72, CF81, CF82, CF83 |
| West Glamorgan | SA1, SA2, SA3, SA4, SA5, SA6, SA7, SA8, SA9, SA10, SA11, SA12, SA13, SA80, SA99 |
| South Glamorgan | CF3, CF5, CF10, CF11, CF14, CF15, CF23, CF24, CF30, CF61, CF62, CF63, CF64, CF71, CF91, CF95, CF99 |
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The point that I am trying to make is that the table on Wikipedia uses postal counties, which are not the same as actual counties as they are used on this site. As a fun example I just found with Wales:
This Domino’s pizza and this plumbing supply store both have a CH4 post code, but one of them is in England and the other in Wales. Post codes and postal counties apparently do not even follow country lines.
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Ah my bad. I actually had the reverse situation in my head so probably misread earlier posts. I was thinking towns would cross counties but postcodes would generally be a small enough area that this wouldn’t happen. I didn’t realise this could happen at a postcode level. It’s actually kind of incredible in a bizarre way.
Oh well, the tables I posted can at least serve as a rough guideline I suppose.
