Datasets:

markmclaren
/

inspired-postcodes

license: other
license_name: open-government-licence-v3
license_link: https://www.nationalarchives.gov.uk/doc/open-government-licence/version/3/
tags:
  - geospatial
  - postcodes
  - gb
  - pmtiles
  - vector-tiles
  - inspire
  - land-registry
pretty_name: Inspired Postcodes — GB Postcode Boundaries (PMTiles)

Inspired Postcodes

GB postcode boundary polygons derived from open Land Registry and ONS data, published as PMTiles vector tile files.

Interactive map: markmclaren.github.io/inspired-postcodes

The approach was inspired by Mark Longair's blog post: Open Data GB Postcode Unit Boundaries

Mark's Voronoi-processed postcode data, derived from Mapit, is also available as PMTiles: github.com/markmclaren/mapit-postcode-pmtiles — live viewer

Files

File	Layer name	Description
`inspire_original.pmtiles`	`inspire`	All INSPIRE property boundary polygons. Where a parcel spans multiple postcodes, it is split into segments using Voronoi cells seeded from UPRN coordinates. No-postcode parcels are retained.
`inspire_single_pcds.pmtiles`	`inspire`	Property parcels that map cleanly to exactly one postcode. Parcels with multiple or unresolved postcodes are excluded.
`inspire_dissolved_pcds.pmtiles`	`pcds_dissolved`	Postcode unit boundaries (e.g. `AB10 1AB`), formed by dissolving all single-postcode parcel geometries by postcode.
`inspire_sector_dissolved_pcds.pmtiles`	`pcds_sector_dissolved`	Postcode sector boundaries (e.g. `AB10 1`), formed by dissolving the unit boundaries.
`inspire_district_dissolved_pcds.pmtiles`	`pcds_district_dissolved`	Postcode district boundaries (e.g. `AB10`), formed by dissolving the sector boundaries.
`inspire_area_dissolved_pcds.pmtiles`	`pcds_area_dissolved`	Top-level postcode area boundaries (e.g. `AB`), formed by dissolving the district boundaries.

All parcel-level layers (inspire_original, inspire_single_pcds) include the following properties:

Property	Description
`pcds_single`	The single postcode assigned to the parcel (e.g. `AB10 1AB`).
`uprn_count`	Number of UPRNs within the parcel.
`pcds_count`	Number of distinct postcodes within the parcel.
`colour_index`	Integer (0–5) for neighbour-contrast polygon colouring.

Dissolved layers include the postcode key for their level (pcds, pcds_sector, pcds_district, or pcds_area) plus source_unit_count and source_polygon_count.

How the Data Was Produced

The pipeline was run on the Isambard 3 HPC system using a set of Python/DuckDB scripts and Slurm job definitions.

Download INSPIRE GML zip files (one per local authority, ~318 councils for England and Wales) from the HM Land Registry INSPIRE download service.
Load each GML into DuckDB via GDAL/ST_Read, with offline GML sanitisation to avoid remote schema fetches on HPC compute nodes.
Enrich polygons with postcode data by spatially joining NSUL UPRN points (converted from EPSG:27700 to WGS 84) onto each parcel.
Split multi-postcode parcels by constructing Voronoi cells from the UPRN point coordinates within each parcel and intersecting them with the original polygon.
Export to newline-delimited GeoJSON per council.
Tile each GeoJSON to MBTiles with Tippecanoe (zoom 0–16, geometry simplification, no tile size limit to prevent feature dropping at low zoom).
Merge all per-council MBTiles with tile-join, then convert to PMTiles with the pmtiles convert CLI.
Dissolve the single-postcode merged layer progressively by postcode unit, sector, district, and area (with a 2 m buffer to close small gaps between adjacent parcels before union), producing four dissolved PMTiles outputs.

Data Sources

INSPIRE Index Polygons — HM Land Registry Cadastral Parcel data for England and Wales. use-land-property-data.service.gov.uk/datasets/inspire
National Statistics UPRN Lookup (NSUL) — ONS dataset mapping Unique Property Reference Numbers (UPRNs) to postcodes and British National Grid coordinates (December 2025, Epoch 123). geoportal.statistics.gov.uk/datasets/4e0b4b3fbc2540caae27e7be532e61be

Inspired Postcodes

Files

How the Data Was Produced

Data Sources

Licence