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National Address Gazetteer infrastructure

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How does GeoPlace ensure the quality of data within the National Address Gazetteer infrastructure

GeoPlace receives over 6,500 update files per month from local authorities in England and Wales. Across local authorities as a whole, there are around 2 million records modified and sent to GeoPlace each month.

Once the records are received from local authorities, GeoPlace undertakes a large data validation exercise testing the incoming LLPG and LSG data against the Data Transfer Format (DTF) and the Data Entry Conventions (DEC) specifications. Both NLPG and NSG are then compared against each other to highlight any street record anomalies.

A series of 500 health checks are also carried out on the two datasets. Further checks are carried out on logical data consistency, classification and address mismatches between the NLPG, Ordnance Survey, Valuation Office Agency and Royal Mail's Postcode Address File (PAF) to form the National Address Gazetteer Database based upon the use of the UPRN and USRN.

By taking data from multiple sources; local authorities, Ordnance Survey, Royal Mail and the Valuation Office Agency and validating it against each other, GeoPlace can be confident that change intelligence on the ground is captured.

In addition to the work carried out ensuring data conformance, GeoPlace works to ensure the product is fit for purpose and meets user requirements from both the public and private sector.

GeoPlace has achieved certification to two industry recognised and highly respected international standards, namely ISO9001 for Quality Management, and ISO/IEC27001 for Information Security. Certification to these standards is part of GeoPlace's drive for quality, accuracy, and security for all the work we do.


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.

Local authorities provide their address update records to us on a continuous basis for inclusion in the National Address Gazetteer infrastructure. The National Address Gazetteer infrastructure contains over 40 million addresses. In every six weekly cycle we synchronise 2,599,000 changes and carries out a total of 3,440 data validation checks.

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.