Code-Point with Polygons Overview

This overview introduces Code-Point with Polygon, giving context for all users – highlighting key features, providing examples of uses, and listing details such as file sizes, supply formats, etc.

Code-Point with Polygons is a dataset that contains the notional area of postcode units, allowing customers to display and analyse any data collected at the postcode level.

The polygons within the product are derived from georeferenced Royal Mail Postal Address File (PAF) delivery addresses. A process is undertaken to create a set of polygons around individual address records within a postcode. This is called a Thiessen process and the polygons are the result of a mathematical computation that creates polygons from point data. In this way, mathematically consistent boundaries are created between distinct postcode groups, creating this notional boundary set.

Set of notional postcode boundaries within Code-Point with Polygons

Postcode unit boundaries are, by definition, only the delivery point or collection of delivery points that constitutes the postcode units. The boundary is therefore a notional one, the position of which is arbitrary. What has been created, however, is a set of boundaries that follows a consistent logic and portrays the notional footprint of each postcode unit. The boundary encloses every delivery address for which positional data of sufficient quality is available, and which follow major physical features that could reasonably be regarded as part of the postcode boundary.

Key features of the product

The key features of the Code-Point with Polygons product are as follows:

• A set of 120 postal-area-based files that provide a set of boundaries for the postcode units in Great Britain for shapefile, TAB and MID/MIF supply formats. For vector tiles and GeoPackage supply formats, a single national file is provided.

• Vertical_streets: A list of polygons for locations that contain more than one postcode, for example, office blocks and flats.

• Corresponding Code-Point information providing the number of delivery addresses and the health and administrative area codes related to each postcode.

Uses of Code-Point with Polygons

The quality of this polygon creation allows the polygons to be used for a wide range of applications. This will include analysis of geographically based information or statistics by postcode, and the pictorial display of information that has been analysed or sorted by postcode.