These are digital boundaries for the system of Constituencies which were and are the units from which Members of Parliament are elected, and which they then represent. The system of county and borough constituencies has early origins but was not systematically mapped until the reforms introduced by the Representation of the People Act in 1832. This file represents the system as it was established following the Boundary Commission Report of 1918. 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. Great Britain Historical GIS Project. (2009). Parliamentary Constituencies of England, 1918-1945. University of Portsmouth. Available at: http://purl.stanford.edu/ky693nv1329. Gregory, I, Bennett, C, Gilham, V., and Southall, H. 2002. The Great Britain Historical GIS Project: from maps to changing human geography.' The Cartographic Journal, Vol. 39, No. 1, p. 37-49. Southall, H 2012, 'Rebuilding the Great Britain Historical GIS, part 2: a geo-spatial ontology of administrative units' Historical Methods: A Journal of Quantitative and Interdisciplinary History, vol 45, no. 3, pp. 119-134. DOI: 10.1080/01615440.2012.664101 This layer is presented in the WGS84 coordinate system for web display purposes. Downloadable data are provided in native coordinate system or projection.