https://www.walesonline.co.uk/news/wale ... d-15909210
If you've ever lived in Cardiff you'll know that the postcodes don't really make sense.
Admittedly it's not something that keeps Cardiffians up at night, but when you sit down and think about it the whole system seems a bit weird.
In other cities across the UK, such as Swansea and London, they appear to follow a much more logical approach.
Properties in the centre have postcodes with lower numbers, such as SA1, and it goes up as you move further out.
But in Cardiff it appears to be all over the place.
Buildings right in the middle of the city are CF10, but as you move further away people have CF5 postcodes.
And unlike a lot of cities, Cardiff doesn't doesn't even have a CF1 - but 20 years ago it did.
At one time some properties in Grangetown had the CF1 postcode, but the whole system was changed in 1999.
A Royal Mail spokesperson said: “Originally the ‘CF’ postcode area did include lower numbered postcodes. However for operational reasons it was necessary for Royal Mail to undertake a recoding exercise of the town in 1999, which resulted in changes.
"A number of cities in the UK have been recoded due to either growth in the number of delivery points or changes in town planning; so it is not uncommon for the central postcode in a city or town centre to be a number other than one.”
But as to why particular codes like CF24 exist, while CF1 doesn't, the Royal Mail said they couldn't provide any further information.
Ever since the change, the system starts at CF3 with a load of numbers missing all together.
Now CF5 covers a huge area from Leckwith to Wenvoe, with CF10 covering the city centre and the Bay.
According to map experts Map Marketing, postcodes were originally developed to help streamline postal delivery.
They said that a postcode is a group of between five and seven letters and numbers that identify a group of houses or addresses.
The postcode is split into two parts, an outward and inward code, separated by the space in the middle.
Each full postcode contains an average of 15 delivery points and each postal delivery takes place in two stages.
When a letter is collected it is routed to a main sorting office identified within the first part of the postcode, the outward code.
The local sorting office uses the second part of the postcode, the inward code, to direct a letter right down to the individual postman’s walk.
Take for example the postcode CF5 2GY.
CF refers to one of the 124 areas in the country.
CF5 refers to the district postcode . There are on average 21 districts in each area, with around 8,200 delivery points in each district.
CF5 2 refers to the sector postcode which refers to one of the sectors each district is segmented down into.
CF5 2GY refers to the final level of the postcode, the unit postcode , which pinpoints a group of houses or addresses.
Some organisations are allocated a unique postcode to ensure the segregation of large deliveries of mail to a single address.
If an organisation receives, on average, 50 or more items of mail a day, then a large user postcode may be allocated.
Map Marketing said there are a number of reasons postcodes can change.
They said: "For example, new building developments, both residential and business (eg. housing estates and business parks within an already densely populated area), may lead to postcode exhaustion thereby leaving no free postcodes to allocate.
"Because of the geographical nature of the postcode system it is necessary to consider the wider area and allocate new postcode segmentation."