Failure to do so just means you'll find it hard to take out loans or get credit, since the electoral register is the first port of call for anyone wishing to confirm your name and address. Though the downside is that it also helps debt collection agencies find you. And gets sold on to junk mailers .... But who cares? Unless you don't want anyone to know where you live?
btw I have never voted (but then, I am only 45).
Edit: oh, and they "threatened" you last year and the year before and the year before that and ........ But you filled it in okay last year - so why now suddenly get all upset about something you've probably been doing and knowing the consequences of not doing, for decades?
edit on 13-9-2011 by Essan because: (no reason given)