Boundary-Line is the key dataset of administrative and voting boundaries in Great Britain. It is a representation in computer-readable form of a specialist large-scale map, including real-world objects, which may be tangible (such as the mean high water mark) or intangible (such as a district boundary).
GIS software provides the functionality to store, manage and manipulate this digital map data. The properties of the data make it suitable as a key base for users wishing to develop applications. Boundary-Line is also suitable for use within other digital mapping systems. It's coordinated on the National Grid, which allows for the easy superimposition of other datasets.
Polygons are continuous areas defined by sets of bounding closed lines. They are representational of areas, such as electoral wards, and have relationships to administration collection features in order to convey descriptive characteristics of the polygon. These are explicit within the data and can be viewed and manipulated with appropriate software.
Boundary-Line is currently updated by mapping against OS VectorMap Local (1:10 000 scale) and, in certain cases, large-scale sources.
A list of the features within Boundary-Line includes:
Area measurements
Civil parish (England) and community (Wales)
County
Distinctive names
District
Electoral division (county and unitary)
English region
Extent of the realm (EOR): either mean low water mark (England and Wales), mean low water springs mark (Scotland) or seaward boundary extensions
Greater London Authority
Greater London Authority Assembly constituencies (the London proportional representation voting areas)
GSS codes in England, Wales and Scotland for all units, with the exception of Greater London Authority, county electoral divisions and non-civil-parish areas
London borough (including the county of the City of London)
Mean high water mark (England and Wales) and / or mean high water springs mark (Scotland): both are abbreviated to MHW in product documentation
Metropolitan district
Scottish parliamentary constituency and electoral region
Unitary authority
Unique administrative unit, link and polygon identifiers
Ward (district, unitary, metropolitan and London borough)
Welsh Parliament constituency and electoral region
Westminster (parliamentary) constituency
There are several supplementary layers included alongside the main Boundary-Line product. These supplementary layers sit separately to the main GB Boundary-Line folder and are included as separate directories in the shapefile and MapInfo TAB file formats.
Features included as supplementary in the supplementary directory are:
Historical counties
Ceremonial counties
Historical European regions (frozen as of 1 April 2021)
Country
This overview introduces Boundary-Line and gives context for all users – highlighting key features, providing examples of potential uses, and listing details such as file sizes, supply formats, etc.
Boundary-Line provides a representation of the hierarchy of administrative and electoral boundaries and their names for England, Scotland and Wales. Boundary-Line for England and Wales was initially digitised from Ordnance Survey’s boundary record sheets at 1:10 000 scale (or, in some cases, at larger scales).
The Government Statistical Service (GSS) codes are supplied by the Office for National Statistics (ONS) and General Register Office for Scotland (GROS).
Appropriate software is needed to use the data for your intended application.
The high specification of Boundary-Line offers you the following benefits:
Full coverage of Great Britain, supplied as England, Scotland and Wales.
The key boundary dataset for Great Britain, suited to multiple applications using a geographical information system (GIS) and other digital mapping systems.
The full hierarchy of boundaries.
Structured vector format, offering great functionality.
GSS codes, where available, which allow you to link Boundary-Line polygons with GSS information.
Area values for every polygon.
Mean high water (springs) mark, which enables you to build and explicitly identify dry land areas within coastal polygons.
Documented updates via bi-annual releases allow you to easily identify relevant changes.
Unique administrative area identifiers are retained at each update, allowing revised boundaries to be related to your existing data.
Boundary-Line can be used for GIS analysis to support a wide range of business decision-making, such as:
Political analysis
Environmental analysis
Statistical analysis for social or marketing decision-making
Geo-demographic analysis
Asset management
Planning applications
Legal work
Reference and research
Customised graphic output
Boundary-Line is available in the following formats:
Esri shapefile
MapInfo TAB file
GeoPackage
Geography Markup Language (GML)
Vector tiles (MBTiles)
Boundary-Line can be freely downloaded under the Open Government Licence. Data can be downloaded in various formats from the Ordnance Survey Data Hub.
Boundary-Line is updated twice a year, in spring and autumn, allowing a choice as to which update is preferred.
The spring update represents boundaries (as defined and modified by Orders, Acts and Statutory Instruments) at the date of the May local elections.
The autumn update also represents boundaries at the date of the May local elections and is operative from the previous spring / May to autumn / October release.
Unlike changes to other boundaries, changes to Westminster constituency (parliamentary) boundaries do not come into operation on a defined date, and it is therefore difficult to timetable such changes into the spring or autumn updates. Therefore, any forthcoming Westminster constituency (parliamentary) boundary changes that have been approved by Government will be supplied as a separate file (in MapInfo TAB or Esri shapefile formats only) as part of the updates until they are included in the product.
