These are digital boundaries for the system of counties used in England and Wales for vital registration and also for the administration and reporting of the Census of Population. They were defined as aggregates of Registration Districts and existed only for purposes of statistical reporting. They differed significantly from both Ancient and Administrative Counties, which the same censuses often also reported on. This file represents the system as it was used to report the 1851 Census of Population. Statistical data and other information used in “A Vision of Britain through Time” can be accessed here: http://www.visionofbritain.org.uk/data.This dataset is intended for researchers, students, and policy makers for reference and mapping purposes, and may be used for basic applications such as viewing, querying, and map output production, or to provide a basemap to support graphical overlays and analysis with other spatial data.