I entered into a rather ill-tempered argument with a stranger yesterday. It started going downhill when he asserted that there were in fact 90 million people in the United Kingdom, not the 60 that I quoted from my memory of the last time I looked at the ONS figures. "But they miss all the illegals," he said.
Whilst of course census information is always inaccurate and incomplete, I was wondering what methods the ONS uses to compensate for this in order to produce a figure good enough for the government to use.