Every registered freehold in England and Wales has a shape. A boundary drawn round it, sitting in a public dataset, free to download. Millions of them. The land between those shapes, the bits with no polygon at all, is where it gets interesting.

Those shapes are INSPIRE Index Polygons. If you want to go looking for unregistered land in the UK, this is the raw material. So it's worth knowing what the data actually is, what it quietly leaves out, and how to wrestle it into something you can look at.

What INSPIRE actually is

INSPIRE is an EU directive. Infrastructure for Spatial Information in the European Community, if you want the full mouthful. The idea was to get public bodies across Europe publishing their spatial data in a common, open way, so it could be found and used rather than locked in a filing cabinet.

The UK implemented it like everyone else, and one of the things that fell out the other side was HM Land Registry publishing the boundaries of registered freehold land. They call them INSPIRE Index Polygons.

Brexit didn't undo this. The dataset is still published, still updated, still free. The directive was the reason it exists. It carries on regardless.

What the dataset contains

Each polygon is the indicative boundary of a registered freehold parcel, with an ID. That's pretty much it.

A shape. A reference number. The outline of a registered title, drawn on the map.

What it gives you is coverage. Pan across England and Wales and you can see, parcel by parcel, what's registered as freehold and what isn't. The gaps are the point.

What it does NOT contain

This is the part people trip over, so read it twice.

The polygons do not tell you who owns anything. No names, no proprietor, no company. That information sits in a different place, behind a paywall, and you buy it title by title if you want it.

They do not include leaseholds. This is the freehold index. Flats, leasehold estates, all of that is a separate dataset.

They do not give you legal boundaries. HM Land Registry works on what's called the general boundaries rule, which means the line you see is indicative, not the precise legal edge of the land. Close enough to find a parcel. Not close enough to argue a fence in court.

And a gap in the polygons does not automatically mean the land is unregistered. It might be. It might also be a parcel that's registered but didn't make it cleanly into this particular dataset. The map is a starting point for a question, not the answer to it.

Why there are gaps at all

It helps to know why a country in 2026 still has unregistered land. Registration wasn't always compulsory. For a long stretch of the twentieth century you only had to register a title when the land changed hands, and even that came in gradually, area by area, before it applied everywhere.

The whole of England and Wales has only been under compulsory registration since 1 December 1990, when the Registration of Title Order 1989 finished the job. Some areas came in late. Cornwall and Devon only fell under it in 1990, which is part of why there's still so much unregistered land down here.

So the trigger is a sale. Land that's been bought and sold in recent decades is almost certainly registered. Land that hasn't, the field passed down through a family, the strip nobody's transacted, the parcel sitting in an old estate, may never have hit the register at all.

That's the pattern behind a lot of the gaps. Not lost land. Just land that never had a reason to be written down. Which is exactly why the forgotten, the inherited, and the never-sold turn up as blanks on the map.

Licensing: you're allowed to use it

The good news. The INSPIRE Index Polygons are published under the Open Government Licence. That means you can use them, including commercially, as long as you attribute the source. Build a product on them. We did.

It's been free to download since 2013, but the terms back then were more restrictive. The proper open release came on 1 July 2020, when HM Land Registry moved the data to the Open Government Licence. That's the version that lets you actually build on it, so if you read older guidance moaning about the licence, it's out of date.

There's an attribution line HM Land Registry asks you to include. Use the one they specify on the dataset page rather than guessing at it.

How to download it

The polygons live on the Use land and property data service on gov.uk. No account needed for the INSPIRE download.

It comes split by local authority area. So you don't grab one giant file, you grab a pile of smaller ones, one per council, each a zip. If you want the whole of England and Wales you're downloading a lot of zips and stitching them together.

Fine for a county. A faff for the lot.

The format quirks

Inside each zip is a GML file. Geography Markup Language, which is XML with coordinates in it. Verbose, heavy, and not something most mapping tools will open directly.

The geometry comes in ETRS89 latitude and longitude, which is the coordinate reference system INSPIRE mandates. Not British National Grid, which is what a lot of UK data uses, and not the Web Mercator your slippy map probably expects. So at some point you will be reprojecting coordinates, and if your parcels end up in the sea off the coast of Africa, that's why.

The files are big. All those polygons, all that XML overhead. Plan for it.

Tools to turn it into something usable

Here's the actual pipeline, the one we run.

GDAL, specifically ogr2ogr, reads the GML and converts it to something saner like GeoJSON, reprojecting as it goes. One command does the format change and the projection change together. It's the workhorse for this kind of thing and it's free.

Then, if you want it to render quickly over a whole country rather than choking the browser, you build vector tiles. Tippecanoe takes your GeoJSON and turns millions of polygons into a tiled pyramid that only loads what's on screen.

We pack the result into PMTiles, a single-file tile format that serves straight off object storage with no tile server running. GML in one end, a fast map out the other.

None of this is magic. It's an afternoon of command-line work the first time, and most of it is waiting for the conversion to finish.

The limitations, honestly

Freeholds only, as covered. No leaseholds, no ownership, indicative boundaries.

You'll also meet slivers. Tiny gaps and overlaps between adjacent polygons that are artefacts of how the boundaries were digitised, not real strips of unregistered land. Learn to tell a genuine gap from a one-metre digitising wobble or you'll chase ghosts.

And it's England and Wales. Scotland has its own registry, Registers of Scotland, and its own data. Northern Ireland too. INSPIRE Index Polygons stop at the border.

Where this gets used

Researchers, journalists, planners, and a steadily growing number of curious people who want to know who owns what, all use this dataset. It's the open backbone of land transparency in England and Wales.

And it's what sits under Edgelands. We've already done the download-convert-tile dance for the whole of England and Wales, so instead of a weekend with GDAL you pan around a map with every registered freehold drawn on it and the gaps left showing. Spot a patch nobody's drawn a polygon over, and start asking questions. £5 a month, 7-day free trial.

Edgelands is a research tool built on this open data: it maps the gaps so you don't have to run the pipeline yourself. Finding a gap is the start of a question, not the end of one, and the next step in answering it is usually a solicitor who does property work.

So, worth knowing

INSPIRE Index Polygons are the free, open map of registered freehold England and Wales. Indicative boundaries, no names, no leaseholds, but complete enough that the gaps mean something.

You can download it and build the map yourself, GML and ogr2ogr and a long coffee. Or you can let someone else do the faff. Either way, it starts with the same idea: most of the country is mapped, and the interesting bit is what isn't.

Want the why-it-matters version rather than the data one? Start with how to find unregistered land in the UK, then read up on adverse possession and the 12-year rule.