The unusual London postcode system dates back to WWI. The whole city is divided up into districts denoted by a letter (or letters) and a number. For example, W1, the postcode for Mayfair and Soho, stands for ‘West London, district 1’. EC1, on the other hand, stands for ‘East Central London, district 1’. The number a district is assigned has nothing to do with its geographic location, but rather its alphabetical listing in that area. For example, in North London N1 and N16 are right next to each other, as are E1 and E14 in East London.