List of United Kingdom censuses
The census in the United Kingdom is decennial, that is, held every ten years, although there is provision in the Census Act 1920 for a census to take place at intervals of five years or more. There are actually three separate censuses in the United Kingdom – in England and Wales, Scotland, and Northern Ireland – although they are often co-ordinated.
Source: Wikipedia — List of United Kingdom censuses (CC BY-SA 4.0)