Supporting Authority Split with National Street Gazetteer

The Problem: With Cumbria’s transition from a county and six districts into two new unitary authorities, the single Cumbria NSG had to be divided. The challenge was ensuring every street, ESU, and USRN was correctly allocated to the appropriate new authority, while preserving data integrity and continuity of service for critical users such as emergency services, utilities, and local authorities.

Background

Cumbria County Council, working with its six district councils and supported by software supplier WDM, was responsible for maintaining the Cumbria National Street Gazetteer (NSG). Following local government reorganisation, this work transitioned to the new unitary authorities of Cumberland and Westmorland & Furness.

The National Street Gazetteer (NSG) is the central, authoritative database of all streets in England and Wales. It provides consistent, accurate information through Unique Street Reference Numbers (USRNs), enabling reliable communication across public services, utilities, and emergency responders. In Cumbria, the NSG was managed as a countywide gazetteer, with district councils supplying local updates. The government’s decision to reorganise Cumbria into two unitary authorities — Cumberland and Westmorland & Furness — required splitting this single system into two operational gazetteers.

The Challenge

Splitting the Cumbria NSG was not a simple administrative change but a highly technical project. The existing dataset contained thousands of interlinked records, many of which crossed new authority boundaries. Streets, ESUs, and USRNs had to be carefully reassigned or recreated where necessary. The process demanded new database structures, accurate boundary mapping, and the creation of additional Type 3 USRNs for streets spanning both authorities. Moreover, the project needed to be completed in time for the April 2023 reorganisation, without interrupting service delivery or compromising the accuracy of street data relied upon nationally.

The Solution

A phased and collaborative approach was adopted. WDM and the NSG custodian created polygons for the new authority areas and introduced a new database field (new_authority_uid) to assign records systematically. Spatial queries and mapping layers identified affected ESUs, while new Type 3 USRNs were created for streets crossing authority boundaries. Multiple dry runs tested the splitting scripts, with record counts compared to ensure data integrity. GeoPlace provided independent validation, and anomalies were corrected in consultation with district custodians. Continuous communication and early preparation allowed the project team to deliver two fully functional and accurate gazetteers by the April 2023 deadline.

Industry Impact & Recognition

The Cumbria NSG split showcased how complex local government reorganisations can be delivered without service disruption. The project provided a clear, repeatable model for other regions facing similar restructuring. It highlighted the importance of early planning, robust testing, and cross-organisational collaboration, setting best practice for the addressing and street data community. By maintaining accuracy and continuity throughout the transition, the project reinforced the NSG’s role as a trusted national dataset. The successful delivery was widely recognised within the industry as an exemplar of effective technical execution and collaborative working.

Conclusion

The successful division of the Cumbria NSG into two fully operational gazetteers for Cumberland and Westmorland & Furness was a significant achievement. The project combined technical innovation with strong partnership working, ensuring the reorganisation was delivered smoothly and without disruption. By beginning preparations early and maintaining close collaboration across all stakeholders, the team created a solution that safeguarded critical services and set a benchmark for future authority reorganisations. The Cumbria NSG case study demonstrates the value of proactive planning, rigorous testing, and shared expertise in delivering complex national data projects.