The 21 censuses that have been conducted in Britain since 1801, have provided an invaluable insight into Britain-s social, political and economic history over the past 200 years. From their original purpose to assess how many men were fit for military duty in the Napoleonic wars, to being a necessary tool for determining government policy, the 10-yearly census return is a fascinating snapshot of the state of the population on a particular moment in each decade. The growth of Britain-s cities; the movement of population away from the countryside; the variety of people-s occupations; their way of life; and what religious beliefs they hold are all contained within the census reports. With the imminent publication of the 1921 census results, this will prove a useful introduction, both for those interested in general trends in social history, and those researching family history.