Censuses past

Although the census collects data on every member of a household, this is not its main objective. Its aim is to compile statistics. These are used by government, organisations and businesses for planning purposes and targeting resources and services.

Censuses are not new. England's first modern census was taken in 1801 - though 1841 was the first detailed survey.

At the time, information from the returns was handwritten by clerks into enumeration books. In 1911, punch cards were first used for processing the information and computers were introduced in 1961.

The data gathered has changed over time - from questions on flush toilets in 1951 to student accommodation in 1981. Reflecting a growing diversity, questions on ethnicity and religion have been added in the last 30 years.

To protect personal information, the census is closed to public access for 100 years - although statistics derived from it are available much sooner. Once opened, they are an invaluable tool for family historians, and can reveal much about social life in the past.