Understand the way the UK postcode system works, and you or your company will benefit. A UK postcode is a two-part code – an Outward Code and an Inward Code. For example: TW1 4YR. The TW1 is the Outward Code, and ensures the letter gets to the town of Twickenham. The Inward Code – 4YR helps direct the item to the post person who is going to deliver to that address. It is preferred to have the complete postcode, but sorters are able to work with only the Outward Code.
With this information, they can forward the item to an LDO (Local Delivery Office) and let the LDO deal with it using their knowledge of the local community. What makes the UK postcode system unique is that there are three different systems in operation: single letter codes for certain major cities, two letter codes for other towns and cities, and a zone system which applies to London only