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National Address Gazetteer infrastructure


What is the role of custodians and SNN officers in the creation of the NAG infrastructure?

District and Unitary Authorities have a statutory responsibility to name streets and number properties. This street naming and numbering (SNN) information is combined with other information to produce the Local Land and Property Gazetteer (LLPG). The LLPG is the mechanism to electronically capture property addresses and streets in accordance to the BS7666 format.

Authority updates are supplied from the LLPG by address contributing authorities to GeoPlace on a regular basis. GeoPlace combined this local intelligence with other national data sources to produce the National Address Gazetteer infrastructure which in turn form the AddressBase range of products, made available through Ordnance Survey.

We manage the National Address Gazetteer infrastructure which is the data storage and set of processes bringing together the existing local authority sourced addressing datasets together with Ordnance Survey, Valuation Office Agency and Royal Mail data. Through agreement between Ordnance Survey and Scotland's Improvement Service, working on behalf of Scottish Local Government, the National Address Gazetteer includes Scottish address data.

GeoPlace is the central source for UK addresses and streets. We work contractually with all 339 councils in England and Wales which have statutory responsibility for approving and creating addresses.  We manage a central hub of 44 million addresses and 1.39 million streets, taking feeds of address and street data from local authorities in England and Wales, central government, Ordnance Survey, Royal Mail and data from Scotland, Northern Ireland, Isle of Man and the Channel Islands via the Improvement Service, Land & Property Services, Isle of Man Government and Digimap respectively.

Through a stringent data quality process, we synchronise and match data against records from several authoritative government property and address databases. Through a validation and assurance process we run 364 Address data checks and 550 Street data checks on each record before being accepted into the database. Data is enriched and transformed by adding the best attributes from source datasets to enhance overall quality of the product.  Around 2 million records are updated monthly.

Working through a governance structure, we agree, monitor and support an annual data improvement process with councils which set levels of data quality, completeness and accuracy.

The result is a single, unified source for all addressing and street data used for streetworks, as mandated by the New Roads and Street Works Act 1991 and distributed by Ordnance Survey through the AddressBase range of products.



From NAG to AddressBase

The National Address Gazetteer infrastructure is the single source from which AddressBase products are developed and made available by Ordnance Survey. 

AddressBase® Premium, available from Ordnance Survey, is the most comprehensive and accurate geographic dataset of 40 million addresses, properties and land areas where services are provided. 

Thanks to the relationship with local authorities, users of AddressBase benefit from the most in-depth view of addresses throughout the property lifecycle – from planning permission, through construction, occupation and change of use to demolition and beyond.