New number plates - from September 2001 - change every six months. 1st half starts March - 2nd half starts September. The format since then has been two letters, known as 'local memory tags', two numbers to indicate the year of registration [first or second half] known as 'age identifiers', followed by three more letters known as the 'random element'. From March 2010, the age identifier will be 10, changing to 60 in September 2010. In March 2011, the age identifier will be 11, changing six months later to 61. DVLA says this pattern will continue until all permutations are exhausted. Local memory tags show in which part of the country a vehicle was first registered. For example, London registrations start with the letter L, while West of England registrations, which include Exeter, Truro and Bristol local offices, start with a W.