The UB postcode area, also known as the Southall (or Uxbridge) postcode area, is a group of eleven postcode districts in England, which are subdivisions of six post towns. These postcode districts cover parts of west and north-west London, as well as a very small part of Buckinghamshire. UB comes from an abbreviation of Uxbridge.
^UB18 includes a series of postcodes where, unusually, the last two letters correspond to the ISO country code for various countries in the trading name of the address, such as "Spring France, GREENFORD, UB18 7FR". Royal Mail – Find an address