What are INSPIRE polygons?

When you look at a land sourcing map and see every plot outlined, you are usually looking at INSPIRE Index Polygons. They are the closest thing there is to a national map of land parcels, and knowing what they do and do not tell you is worth a few minutes.

Where the name comes from

INSPIRE is a framework for sharing spatial data across Europe. To meet it, HM Land Registry published a dataset of index polygons, one for each registered title it holds. The name stuck, so in practice people say INSPIRE polygons when they mean registered land parcel boundaries.

What they show

• The approximate extent of a registered title
• A shape you can measure to estimate plot area
• How land is divided, which makes fragmented ownership and possible assembly opportunities visible at a glance

What they do not show

• The owner. Names sit in the title register, which is a separate paid download from HM Land Registry.
• Unregistered land. Not every parcel has a registered title, so some land has no polygon at all.
• A legally definitive boundary. The polygons are indexing tools, not the official title plan. Treat them as indicative.

How land sourcers use them

The polygons turn a flat map into a map of plots. You can see the shape and rough size of a site, check whether a garden or paddock is a separate title, and find places where several small parcels under different owners could be brought together. From there, an ownership lookup tells you who to approach.

Keep the caveats in mind. Boundaries are approximate, registration has gaps, and the data can lag behind recent splits or transfers. Use the polygons to find and shortlist sites, then confirm the detail through the title register and a proper survey.

INSPIRE Index Polygons are published by HM Land Registry under the Open Government Licence. This guide is general information, not legal advice.