What does a post code say about you? well, it can affect your insurance premiums, and may categorise you demographically. Again, unless it is a service which sends you important mail or one which has a legal obligation or one which could require formal identification, a bogus address and post code will suffice. Most postal districts have their first post code as being <prefix>1 1AB and so on, so it is easy to make up a location central to a given postal district like n1 1ab is probably or at least was at one time the sorting office northampton and b1 1ab the sorting office for birmingham for example, so it is logical to assume a post code of n1 1ac may exist. take a look on google maps to find a postcode of your choice. This evasion is best used for privacy when making cash payments at shops which ask your postcode on the way out as you pay and those which ask you to complete some kind of survey.