Property extents in the United Kingdom
A 'property extent' in the United Kingdom is the exterior boundary line of an owned property. Aka a 'land parcel'.
In England and Wales, Title Plans held by HM Land Registry give the closest idea to the property extent, but even these are not the absolute, legal, binding boundary.
"If you live in England or Wales, there’s usually no record of the exact boundary between 2 properties or who owns the hedge, wall, tree or fence between 2 properties." -- “Your property boundaries”. Retrieved 19 January 2019.
However, HM Land Registry Title Plans are in most cases taken as such. [ citation needed ]
In Northern Ireland https://www.nidirect.gov.uk/articles/searching-the-land-registry
Why does this matter?
The UK does not operate a full Cadastre system.
Various legal checks are performed when land or a property is purchased. Some are compulsory, for example a contaminated land assessment to confirm that a house is not built on top of a waste tip or an ex-factory, and others are advisory, such as a flooding risk assessment.
HM Land Registry
Around 15% of the freehold land in England & Wales is unregistered. Much of this 15% is land owned by the Crown, the aristocracy, and the Church which has not been registered, because it has never been sold -- https://hmlandregistry.blog.gov.uk/2018/02/05/search-owner-unregistered-land/
Until early 19th century: establishing land ownership was based on paper deeds, without a central register. If you wanted to sell a piece of land, you had to show the papers to prove you owned it. This was slow, inconvenient and uncertain.
- 1820s: James Humphreys proposed a central register of land titles to improve efficiency.
- 1860s: Her Majesty’s Land Registry was established. Landowners could choose to register their titles securely with government.
- 1860-1897: Low takeup
- 1897: Land Transfer Act gave local authorities the power to impose compulsory registration. Few counties did so, amid opposition from the legal profession.
- 1990: Registration of land on sale was made compulsory across England & Wales
- 1998: on inheritance
- 2005: under 50% coverage
- 2018: 85% coverage
Difficulties in plotting
Mappers such as the Ordnance Survey can survey and plot obvious boundaries which may be the same as the legal property extent but are certainly not guaranteed.
A property owner is legally required to maintain property boundaries such as fences. This is intended to minimise disputes. So, being able to manually survey a reasonable property extent is feasible. [ citation needed ]
A boundary could be delineated by a thick hedge, in which case the line could be on either side or down the centre.
A canal society want to reinstate an old canal they have found that neighbouring properties had encrouched onto the "no man's land" and now claim ownership of the land. [ citation needed ]
A property may have been bounded by a river or stream. The course of a river can move over time as riverbanks are eroded. The technical property extent does not change.
Difficult to deduce boundary lines from aerial images.
Lack of on-the-ground verifiability.
If the legal boundary differs from the current physical boundary indicators (fences, hedges, rivers, etc.) which would/should OSM include?
See comments on https://hmlandregistry.blog.gov.uk/2018/02/27/drawing-the-line-on-boundaries/ for many examples of difficulty/dispute
INSPIRE Land Registry index polygons
DO NOT USE THIS. It is not proper Open Data as Ordnance Survey have asserted their rights as derived data. [ citation needed ]
OGL licenced INSPIRE Land Registry index polygons? https://www.gov.uk/government/collections/download-inspire-index-polygons
You need to read the license properly, and especially the linked document with "third party conditions" from OS that has all sorts of unacceptable restrictions:
https://sk53-osm.blogspot.com/2013/10/not-very-inspired-land-registry-open.html https://chris-osm.blogspot.com/2013/10/land-registry-inspire-polygons.html https://anna.ps/blog/how-to-use-land-registry-data-to-explore-land-ownership-near-you
Land Registry Prices Paid data
DO NOT USE. This data was (allegedly) entirely run through PAF to enable the LR to sell it, consequently all records contain Royal Mail IPR. The licence condition was changed subsequent to its first release so that it can effectively only be used by estate agents.
Ordnance Survey OpenData
In 2018/19 The UK Geospatial Commission & Ordnance Survey have announced that they will be releasing "property extents"