This file contains the National Statistics UPRN Lookup (NSUL) for Great Britain as at December 2025. The NSUL relates the Unique Property Reference Number (UPRN) for each GB address from AddressBase® Epoch 123 to a range of current statutory administrative, electoral, health and other statistical geographies via 'best-fit' allocation from 2021 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 6 weeks and is designed to complement the Ordnance Survey AddressBase® product. For further technical information about this file, please refer to the User Guide 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 – 487 MB)This release changes allocation of OA21 (E00107679) to Ward WD25. It has been reassigned to E05011642 instead of E05011648. On the November 2025 NSUL, this affected the Ward allocation of 118 UPRNs within the SE region file. See details on our dedicated Notices page. (Note that in the December 2025 NSUL, only 113 of these UPRNs fall in OA21 E00107679.)