What’s The Point Of Postcodes?

At the foot of every British address you’ll find a six-or-seven-character code. It’s perhaps the most important line of your address along with the first – it’ll help the package arrive at the local sorting office, from which most of the hard work will already have been done. It’s allowed sorting to take place with incredible speed and efficiency, and it’s had knock-on benefits in the form of address lookup systems, which with the help of address data cleansing software have helped to ensure that address information is recorded more accurately than ever before.

What’s The Point Of Postcodes?

But this piece of information, for all of the good it’s done, is only a relatively recent innovation. Let’s take a look at the purpose it serves, and just how it came to be.

Anatomy of a postcode

The postcode on the bottom of your address is divided into four discrete chunks.

The first of these is called the postcode area. It’s usually a two-letter abbreviation which refers to a given area of the country. SW, for example, is the South Western and Battersea area of London.

The next part of the code is the postcode district, which refers to the specific area in which the address can be found.

In the second ‘chunk’ of the postcode you’ll find the postcode sector. Generally speaking, each postal worker covers a single sector in a single day.

Finally comes the postcode unit, which generally describes a single street.

At various stages of the sorting office, a given area of the postcode can be quickly examined and filed accordingly. If the entire postcode isn’t a match for the area, then it can be referred back up the line until it eventually arrives at the desired destination.

So how did a system this sophisticated and elegant come to be?

How did postcodes come about?

To trace the origins of the modern postcode, we need to go back to London in the 1850s. At the time, the city was divided into ten postal districts; there was one for each direction of the compass, the directions in between, and a special district in the centre.  Some of these districts attracted more postal traffic than others, and so the less-often-used ones were either abolished or became part neighbouring zones.

This system was straightforward and comprehensible, and so it led to increases in efficiency. As such, it was adopted in other parts of the country. By the turn of the century, similar systems had been implemented in Liverpool and Manchester, and by the end of the second world war Dublin had another system of its own. Over the course of subsequent decades, postcode system would be rolled out in towns across the UK.


While these systems might have led to performance improvements within the cities they were implemented in, the best improvements were yet to come. During the 1950s, the British Post Office began to mechanise its sorting process. Machines were used to ferry packages to the appropriate destinations. These machines were effective; so much so, in fact, that the people using them couldn’t read the address information quickly enough to make good use of them. It was rather like tying a sail to the top of a sports car.

In response, the Post Office considered devising a nationwide scheme that would divide the country into postcodes of the sort we’d recognise today. There was some hesitation, however, which stemmed from the fact that the public had not yet approved of the scheme. And it was the public, recall, which would be writing down those postcodes in the first place.

Norwich was selected as an area for a pilot scheme to be rolled out. The scheme proved a triumph, and in 1965 the then-Postmaster-General declared that the system would be translated into one that could be rolled out across the UK.

This operation was perhaps trickier than many anticipated, as it required existing city-bound postcode systems to be dispensed with in order to introduce the new national postcodes. Eventually, however, the system was fully implemented, and any memory of the old postcode systems faded. The entire system became vastly more efficient, and more-or-less everyone prospered.

The postcode system was supplemented in 2010 with a database that was accessible to private postal companies as well as the post office. This allowed for the development of postcode lookup systems – which would allow the public to more accurately record address information by typing in a postcode and selecting from a list of accurate addresses.

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