Today is Census Day and the date when all households have to report the location of all members of the household as well as information about each person, and the house itself.
This article by Richard Harris from the University of Bristol explains why it is important that you fill in the form, and what happens to the data.
We may find out whether a million people have really left the country, and returned home.
Kit Rackley has also shared some useful links, including the suggestion by Danny Dorling that the Census needs to be repeated in a few years' time.
The BBC News is leading with this story today.