Re: Data protection.
"Also the raw census data doesn't get published for 100 years - at least that's how the law always used to be. I believe the last census to go public was 1911. Great if you're a historian, economist or into family history."
the next one will go live in 2021 (1921 census) but then we'll have to wait a while: the 1931 census (at least for England and Wales) was destroyed in a fire, and the 1941 census didn't happen because the UK had more important things to be getting on with at the time.