National insurance number

[concerned!]

Hi there. Can anyone tell me what the last letter of my national insurance number stands for. It's just that it seems that every one I talk to their last digit is in order of the siblings in thier family i.e oldest ends in A the next in B and so on. However I am the youngest of two brothers and mine ends in C and his in B. Can anyone shed light on this for me please. Thanks!

[Narolines]

Ah - probably me getting hold of the wrong end of the stick; sorry about that.  I sort of assumed A would be the first quarter, and so on.  Actually, don't worry about finding out the details on my account - as long as they don't come after me for more money and I get a pension of some sort when I reach pensionable age I'm not really that bothered what the last letter of my NI number is - if it's important to somebody, he/she probably already knows what it means anyway.........