What is Ordnance Survey? How OS Data Underpins Every UK Property Record
Ordnance Survey is the national mapping agency for Great Britain. Its datasets underpin property addresses, boundaries, and spatial records across government and industry.
Published: 16 Mar 2026 · Updated: 16 Mar 2026 · 6 min read
What is Ordnance Survey?
Ordnance Survey (OS) is the national mapping agency for Great Britain. Founded in 1791, it is a government-owned company responsible for the official, large-scale mapping of England, Scotland, and Wales. Its datasets are used by government, local authorities, emergency services, utilities, and the property industry to understand the physical location and extent of land and buildings.
Unlike HM Land Registry, which records ownership, OS records the physical geography, where buildings are, what shape they are, where roads and boundaries lie, and what every addressable location is called.
Key OS Datasets Relevant to Property
| Dataset | What it contains | Who uses it |
|---|---|---|
| OS MasterMap Topography Layer | Detailed large-scale map of all features: buildings, roads, water, vegetation | Local authorities, utilities, planners |
| AddressBase / AddressBase Premium | Comprehensive address data linked to UPRNs and USRNs | Emergency services, councils, conveyancers |
| OS MasterMap Highways | Road and path network with precise geometry | Navigation, planning, emergency services |
| Open UPRN | All UPRNs and USRNs as open data | Property platforms, researchers, PropTech |
| OS VectorMap Local | Simplified mapping for visualisation | Estate agents, property portals |
The UPRN, OS's Most Important Property Contribution
The Unique Property Reference Number (UPRN) is assigned and maintained by Ordnance Survey through the National Land and Property Gazetteer (NLPG) and its constituent Local Land and Property Gazetteers (LLPGs). Every addressable location in Great Britain, from a terraced house to a telephone exchange, has a UPRN.
In 2020, OS released UPRNs as open data under the Open Government Licence, enabling the property industry to use them freely as a common identifier to link data from different sources. This was a significant moment for property data transparency in the UK.
OS MasterMap and Property Boundaries
OS MasterMap records the outline (footprint) of every building in Great Britain. This is distinct from legal ownership boundaries recorded by HM Land Registry, OS shows where buildings physically sit on the ground, whilst HMLR shows which land is owned by whom.
Property professionals use OS MasterMap to:
- Confirm that a property sits within the title plan boundary
- Identify encroachments or discrepancies between the physical building and the registered title
- Assess the extent of curtilage for planning and valuation purposes
How Property Passport UK Uses OS Data
Property Passport UK uses Ordnance Survey data, including the Open UPRN dataset and AddressBase, to build its property index. Every property record on the platform is anchored to its UPRN, allowing EPC data, HMLR title data, Environment Agency flood risk assessments, and sold price records to be linked accurately to a single, unambiguous property location.
When you search for a property by postcode or address, the OS-derived address data ensures that the correct physical location is identified, even where postal addresses are ambiguous or where multiple properties share similar addresses.
OS Open Data
Since 2020, OS has made a growing number of datasets freely available under the Open Government Licence via the OS Data Hub. Open datasets include:
- Open UPRN
- OS Open Map, Local
- OS Terrain 50 (elevation data)
- Boundary-Line (administrative boundaries)
These open releases have enabled a new generation of property data platforms and research tools to be built on authoritative government geography without licensing cost barriers.
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