Well, I for one have plenty to hide 
I did not fill in a census form in 2001 as I was not in the UK on census night. But I do recall some discussion at the time among colleagues about reluctance to complete it because of home security worries. Of course it is supposed to be confidential, but people can be bribed to disclose things.
Suppose somebody compiled a list of people who apparently lived alone, whose occupation implied that they frequently worked away from home (or on night shifts). They even wanted to know if your home had a ground floor, just to make it easier for the burglars.
Anyway if you don't fancy filling it in, a pleasant and legal way to avoid it is to take a short break abroad over the crucial date
lol now we are getting into deep paranio, same could be said about insurance data bases, car/house,
social security files, child benefit data bases, states single parents, (which i seem to remember a disc was lost)
hospital records. school records,
anyone now working with children, applying for any of the 999 services, etc etc have to now undergo/skip through hoops for them to decide your an upstanding person,
not sure i have seen or filled a census in which makes it clear your away from home (lighthouse keeper may give it away)
a bit like that old chesnut re google street view that the burglars could zoom in on your locks
a local burglar is far more likely to drive down your street at night to get as much/more information on your address,
i live out in the sticks so if i went out and left no lights on/ the alarm not activated etc would give far more away than
a burglar trawling through millions of records to find a snippet of info' on you,
as i said i have no issues whatsoever if people don't want to fill in a census,
and i defend your right to do or not, but i certainly want better reasons than most given
MY opinion, it only hurts your relatives 100 years down the road, having said that hopefully with what we all do now and compile our own tree's most of us will have done all the hard work for them,
i also think with the amount of records now held on computer that future census's may not be that important, but while they are
i suppose i look at it as my part in history, i suppose we all would like to think in years to come we are not forgotten,
my Mum died 30 years ago pretty young and my Dad shortly after, so my grandkids didn't know them but we have photos everywhere and they certainly know ABOUT them so hopefully as they grow older they will remember things,
lol i am rambling, next time you find a snippet of info' re a gt grandparent etc and are pretty chuffed with yourself maybe also give a thought to what legacy even if on paper what you can leave,
lastly i am pretty sure that our relatives would probably not been to keen on filling in the part on the 1911 census about disabilities, so being against the census deffo' aint a new thing.
BTW i would also add i think the fine for not completing is a bit silly, and probably does encourage some to miss or put wrong information, so maybe they should try and come up with a more user friendly way of getting people to fill it in?
