The first official census of the British population was held in 1801. The 1801-1831 censuses were simple counts of the population. Since 1841 there have been decennial* population counts based upon surveys conducted at a household level.
*There was no census in 1941 due to the World War II. In 1966 there was a special interim census.
There are 3 types of census data:
Resources relating to each type of data are described via the tabs at the top of this page.
A guide to the 2001 census : essential information for gaining business advantage by 
Making sense of the census : the manuscript returns for England and Wales, 1801-1901 by 
