This file contains the National Statistics UPRN Lookup (NSUL) for Great Britain as at May 2017. The NSUL relates the Unique Property Reference Number (UPRN) for each GB address from AddressBase® Epoch 48 to a range of current statutory administrative, electoral, health and other statistical geographies via 'best-fit' allocation from 2011 Census output areas (National Parks and Workplace Zones are exempt from 'best-fit' and use 'exact-fit' allocations). The NSUL is produced by ONS Geography, who provide geographic support to the Office for National Statistics (ONS) and geographic services used by other organisations. The NSUL is issued every 12 weeks and is designed to complement the Ordnance Survey AddressBase® product. For further technical information about this file, please refer to the 'Product Specification' document contained within the downloadable zip file. Please note that this product contains Royal Mail, Gridlink, Ordnance Survey and ONS Intellectual Property Rights. (File Size – 374 MB)