Skip to content
  • English
  • Magyar
  • English
  • Magyar

Do British postcodes follow any logic?

Have you ever wondered if the British postal codes follow any logic?l?

I Have! Especially since I had to learn the primary postcodes of the UK for work, so that I can instantly decide whether we cover the area in question and if yes, which colleague to send there. There was no method for that, I just simply had to memorize the list of postcodes. The only advantage I had, is my interest in the UK’s geography, I even enjoyed learning them (apart from one or two exceptions, of course) but often wondering if the British postal codes follow any logic.

postcodes blogpostEverything started with London…

To understand the postcodes, we have to go back in time a little bit. One of the results of the industrial revolution was that life became busy in the UK. With the extension of the railway network, delivery times of posts decreased as more and more people used the service. Having the same street names in several districts of London caused confusion and made the life of the Post Office more difficult. (I would guess most countries and capitols struggle with this phenomenon, my home town, Budapest certainly does with street names like Petőfi utca, Kossuth utca etc.)

In 1857 Rowland Hill split London from its central point to 8 districts according to the compass (N, NE, NW, S, SE, SW, E, W) and split the City to further 2 districts. These were the forerunners of the primary postcodes, which were the applied in every town in the UK by 1860 and by 1934 the whole country was covered (there are 124 primary postcodes in the UK.)

After 1934, the Post Office introduced a number following the primary postcode letters, which was meant to indicate the district (e.g. Birmingham District 1 = B1). The Post Office put some posters on post boxes to help the population know which district they live in. After this only the 50s brought some changes in the life of the postcodes when a new code was required to support the new electric sorting system. A post office general from Norwich, Ernest Marples, came up with the idea of the 6 digit postcode, which was introduced in the UK between 1959 and 1974.

Carlton House Terrace London
To put the British postcodes into perspective, in my home country, Hungary postcodes are numeric and have 4 digits. Codes beginning with 1 equal the Budapest, the capitol, 2 stands for the suburbs and the rest goes clockwise around the country until 9. Interesting I did not know that, I was only aware of the Budapest codes.

So do the British postcodes follow any logic?

A British person would instantly say, YES! And you would believe that and think they do, but then you would think, no they don’t. In fact they do, but from a Hungarian person’s perspective not all the time. The 6 digit codes are alphanumeric, which means they contain both letters and numbers. As a result the number of variation is high, there are 1.7 million postcodes in the UK.

The structure of the code

And what is the structure of the code? The first 2 digits mark the area and I was taught the following number indicates the district which in every town in the UK starts from the middle: 1 is central, 2 is the next one. It is in fact like the layers of an onion. Interesting: Birmingham has 99 districts! The second part of the code means the postcode sector and the postcode unit (streets and house numbers or buildings) In the below example HQ stands for headquarters and as such it means a whole building block.


We work with primary postcodes (letters in fact), e.g. B=Birmingham, L=Liverpool, LS=Leeds, PL=Plymouth, G=Glasgow etc. BS, BN, BT… BS and BT could equally be Bristol but which one is it? And BN and BT could be Brighton. Which one is correct? You have to learn, no excuse or other way of doing it. BN=Brighton, BT=Belfast, BS=Bristol. But then as you start to get out of the confusion, accross comes one like IG which stands for Ilford or SP, Salisbury. My (Hungarian) logic would look for the G in Ilford and for the P in Salisbury but there aren’t any! Or my favourites: FY=Blackpool and TS=Cleveland. No comment. When I see things like that I wonder if the British complicate things on purpose. 🙂

As far as London is concerned I was hoping to find some consistency as N=Northern London, W=Western London, WC=London Western Central, SW=London South Western, SE=London South Eastern I presumed NE being equal to London North Eastern, but no, in fact that stands for North East, Newcastle. Oh dear… 🙂

The Scotts and Welsh are always problematic…

More difficult postcodes for me to learn were some Scottish and Welsh ones which I can not even pronounce properly. KW=Kirkwall, ZE=Lerwick (Shetland-islands), HS=Outer Hebrides and the Welsh ones: LL=Llandudno, LD=Llandridnod. Finally to this wonderful village of Llanfairpwllgwyngyllgogerychwyrndrobwllllantysiliogogogoch (no I cannot pronounce it!) with its postcode of LL61 5UJ should you ever wish to visit.

But how is it in Ireland?

Dublin was divided into 22 districts in 1917 and apart from these, there aren’t any postcodes in Ireland apart from the 22 postal districts of Dublin. However, in 2014 a 7 digit code, the Eircode was introduced, but it does not follow the British logic. The Eircode has been designed to have a specific code for each address, which removes the need for buildings to have numbered locations on the property. It has been criticised several times and is not a solution for the postcode problem in Ireland, because it was not suitable for satnav or Google Maps until 2016. However it is still a confusing system.



All in all I think there is logic in the British postcodes. How much it helps for the post, I do not know, it would be interesting to talk to a post expert. One thing is for sure, the Hungarian postcodes are much simpler.

What do you think?


I made a map using MapPoint about the primary postcodes of the UK as could not find a royalty free image

UK postcodes map

primary postcodes London
Primary postcodes of London
British Isles
Do not forget the isles: Isle of Man, The Hebrides, Channel Islands, Shetland Islands


This Post Has 0 Comments

Leave a Reply

Your email address will not be published. Required fields are marked *

twelve − five =

Back To Top