In the 11th century, of course, things were quite different. If the King said there was to be a survey, you didn’t ask questions, and you certainly didn’t complain. You just told his nice people what they wanted to know.

Nowadays, of course, we’re all much more aware of our rights, and nine centuries of English bloody-mindedness have taught us to cling to them with great persistence. The closest to Domesday that we see today is the compiling of the national census, and even that is fraught with political hazards and public controversy.

Who will be able to see my information? How will it be stored, and what are the safeguards? Will it be anonymous? How can I be sure my confidentiality will be respected and protected?

Apart from the privacy issues thrown up, the big debate that rears its head every time a census is planned is over the question of whether it should be a straight head-count, or based on sampling (calculating based on taking a small number of people to represent the whole country). A head-count may sound like the obvious solution, but it is far more costly than calculating based on a sample, and – perhaps more surprisingly – sampling is in fact usually more accurate than a head-count for many population groups, rather than less.

Why does the method for counting matter?

This discussion may seem like a bit of shadowy maths, nothing that really matters, but in reality the implications can be huge. Consider the case of the United States, where the population of a state determines the number of seats that state has in Congress. Just a few years ago, the US Supreme Court determined that for these purposes the census must be a straight count rather than a sampling exercise, but this means that the groups who traditionally don’t fill in their census forms (people in cities, minority groups in particular) are likely to be under-represented. Watch The West Wing episode "Mr Willis of Ohio" for more…

In the UK people at the younger end of the spectrum have traditionally been the least likely to bother filling out their census forms. This all changed for the most recent census, in 2001. A rumour had spread that filling in the new "Religion" box on the form with the word "Jedi" would lead to the fictional Star Wars faith being accepted as an "official religion". While this isn’t true, it’s believed to have galvanised large numbers of people to fill in their forms who might not otherwise have done. The results of the census revealed that the UK has a staggering 390,000 Jedi, mostly clustered around student towns…