The Census in the UK has been conducted every 10 years since 1801. Over this time there have been numerous changes to the administrative boundaries, such as the amalgamation and deletion of wards and parishes, or the creation of new ones. These occur for a range of reasons, but usually to better distribute the population for administrative purposes.

Without knowledge about boundary changes it can be difficult to understand changes observed in populations, or make comparisons of areas over time. For example, moving a parish boundary may cause a population to increase on paper, within a given parish, but only because part of the population of a neighbouring parish has been incorporated, and not because a sudden influx of new residents.

The Research and Performance team have tried to keep a record of the changes to parishes over time, and the estimated populations as published by each Census, since 1801. This way we are better able to explain apparent changes to the populations estimated by each Census. You will find the most up to date versions of these records on our Open Data portal.