# One sale, two keys

From 28 August 2026, HM Land Registry publishes two lookup tables alongside **Price Paid Data**: one for UPRN and one for INSPIRE ID. They can carry a transaction into other public datasets, but they do not rewrite history or prove who owns a place.

**What you get:** see what each key identifies and where a safe join stops. The demonstration row uses invented labels only.

The decisive source is the [HM Land Registry release](https://www.gov.uk/government/news/hm-land-registry-to-provide-property-identifiers-for-price-paid-data-from-28-august), with the [UPRN specification](https://www.gov.uk/government/statistical-data-sets/technical-specification-transaction-unique-identifier-and-uprn-look-up-table-dataset) and [INSPIRE specification](https://www.gov.uk/government/statistical-data-sets/technical-specification-transaction-unique-identifier-and-inspire-id-look-up-table-dataset). Territory: England and Wales. Edition: July 2026 lookup files. No sales, addresses, prices, coordinates, polygons, or real identifiers are displayed.

## The key is a bridge, not a destination

Price Paid Data has a `transaction unique identifier`. The new tables repeat it in their first column and add, separately, a UPRN or an INSPIRE ID. Match the key, then read the next dataset's definition.

## UPRN and INSPIRE ID do different jobs

A UPRN identifies an addressable location. An INSPIRE ID refers to a polygon for a registered freehold property and shows its indicative position and extent. A UPRN match depends on an AddressBase relationship and may be absent; leasehold and other tenures may be absent from INSPIRE.

## The new bridge is not a universal backfill

HM Land Registry describes the lookup tables as part of the current monthly release. The [Price Paid Data downloads](https://www.gov.uk/government/statistical-data-sets/price-paid-data-downloads) page does not promise here that every previously published row will receive the same keys retroactively. The careful wording is “not promised in this package”, not “can never be found”.

## One transaction can have several INSPIRE IDs

The July INSPIRE file has **82,493 rows** for **77,051 distinct transaction keys**. Local grouping finds at most **41 INSPIRE rows** for one key. “Several” is a lookup-table behavior, not proof that a transaction is wrong or contains several homes.

## A good key makes a question more precise

A UPRN can be used as a parameter in a [Planning Data](https://www.planning.data.gov.uk/docs) query. The research route is: sale row → location → public data about that place. A missing result is not proof that no planning constraint exists.

## An identifier is not a legal verdict

A UPRN is not proof of ownership or occupancy. An INSPIRE ID shows a polygon with indicative position and extent; it is not a definitive cadastral boundary. Neither key says who lives there.

## Three columns tell you whether the bridge holds

Local audit of July 2026 lookup files:

| File | Rows | What was counted |
| --- | ---: | --- |
| UPRN | **94,112** | 94,112 distinct transaction keys |
| INSPIRE ID | **82,493** | 77,051 distinct keys; maximum 41 rows / key |
| Shared keys | **74,000** | distinct keys present in both files |
| INSPIRE fan-out | **4,466** | shared keys with multiple INSPIRE IDs |

Method: count rows in the two archived official CSVs, deduplicate their first columns, then group INSPIRE rows by transaction key. The audit counts lookup files, not all July sales. SHA-256 fingerprints are in `sources/SHA256SUMS`.

### Primary sources

- [HM Land Registry release](https://www.gov.uk/government/news/hm-land-registry-to-provide-property-identifiers-for-price-paid-data-from-28-august)
- [UPRN dataset](https://www.gov.uk/government/statistical-data-sets/transaction-unique-identifier-and-uprn-look-up-table-dataset) and [UPRN specification](https://www.gov.uk/government/statistical-data-sets/technical-specification-transaction-unique-identifier-and-uprn-look-up-table-dataset)
- [INSPIRE ID dataset](https://www.gov.uk/government/statistical-data-sets/transaction-unique-identifier-and-inspire-id-look-up-table-dataset) and [INSPIRE specification](https://www.gov.uk/government/statistical-data-sets/technical-specification-transaction-unique-identifier-and-inspire-id-look-up-table-dataset)
- [Price Paid Data downloads](https://www.gov.uk/government/statistical-data-sets/price-paid-data-downloads)
- [Planning Data documentation](https://www.planning.data.gov.uk/docs)

Next check: when HM Land Registry changes the schema, release boundary, or licence terms; no later than 28 November 2026.