This file contains the ONS UPRN Directory (ONSUD) for Great Britain as at May 2017. The ONSUD 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. The ONSUD is produced by ONS Geography, who provide geographic support to the Office for National Statistics (ONS) and geographic services used by other organisations. The ONSUD 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 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 - 428 MB)This version 2 of the directory contains an amended file for the South East region. The first release had some incorrectly allocated county and local authority district codes for UPRNs in the wards E05010919 - E05010934. (File amended 23/05/17)