David Henwood has a good point - that these numbers provide a clue to people's location in September 1939 (or to their district of birth if born after that date). I can offer my own number, COPG256, having been born in Guildford in the fourth quarter of 1941. I note however that on the actual card, the letters are written separated by full stops (C.O.P.G.), so it might not be that CO is Surrey. One suspects that the code is fairly easily crackable (and carries the sinister idea of being able to generate many people's NHS numbers by simply taking data from FreeBMD). Hector Davie (And PS (pace Iago) - who steals my identity steals trash...)