Developing an excellent address list for Census 2021

Since 1801, the nation has been setting aside one day every ten years to conduct the census, collecting an understanding of all people and households. It is the most complete source of information about the population we have. It is used by central and local government, charities and businesses to help plan the services we all need such as education, healthcare, transport and retail.

To do this the Office for National Statistics (ONS) has used an address register to make sure that every household and managed accommodation in England and Wales gets a census questionnaire. This address register has been used to deliver a letter containing the access code needed to fill in the census online questionnaire.  It will also be used by Census officers to visit and help households that haven’t completed the questionnaire.

For Census 2021, the ONS will be using an address list that’s based on Ordnance Survey’s AddressBase Premium product, and made available by Ordnance Survey through the Public Sector Geospatial Agreement (PSGA).

Over the past three years, GeoPlace has been working closely both with ONS and local authorities to ensure AddressBase Premium is as up to date as possible, particularly on the data associated with communal establishments; tertiary level residential classifications; and student hall accommodation. Over the course of the three years, there has been a 29% improvement in residential records being classified to a tertiary level (ie. detached dwelling) to just over 97%.

It is this partnership between the ONS, GeoPlace, local authorities and Ordnance Survey that has provided the rigour into the resulting address data. Due to their statutory roles around planning and street naming and numbering, local authorities are the originators of addresses and property change intelligence. GeoPlace manages a central national hub, taking feeds from every local authority in England and Wales to develop a consistent national dataset, which is now used by thousands of users right across the public and private sectors as well as the emergency services to support service delivery.

Charlie Dacke, Head of Address Index in Data Architecture, Office for National Statistics said: “The Address Index team at ONS has continued our close working relationship with GeoPlace to ensure the list of residential addresses for Census 2021 was the highest possible quality. As a result, we have been able to share best practice for improving the data and we have avoided duplication of effort. We have jointly created guidance for local authorities for improving their address lists to meet census needs. During the live census operation, we will be using the most up-to-date information available to us through our arrangement with GeoPlace so that we can ensure census forms reach any new and changed addresses.”

Nick Chapallaz, Managing Director of GeoPlace said: “We’ve been working closely with ONS for the past three years to ensure that AddressBase Premium meets ONS’s requirements for a comprehensive address list. The census details collected from householders is a key data source for allocating funding to authorities in England and Wales. It is used by local authorities to target their resources and plan for future demands, so it’s imperative that every citizen is included. GeoPlace’s work has been pivotal in underpinning the method by which we will all benefit from the 2021 Census.”

Find out more about the 2021 Census at and on how the 2021 Census has been addressed at


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