2026-04-13 8 min read

Our Data Source

OpenProp is powered exclusively by HM Land Registry Price Paid Data — the official record of every residential property sold in England and Wales, published under the Open Government Licence (Crown copyright). We cover Greater London only, from January 2010 to the present, representing approximately 1.77 million completed transactions as of April 2026.

Data is updated monthly. Because solicitors have up to 2 months to register a completed sale, the most recent 1–2 months always have lower-than-final transaction counts. Our "current" figures always reference the latest month where volume has stabilised.

Important

Occasionally, HM Registry may edit the dataset without prior notice. We monitor major monthly updates — minor retroactive edits are not individually tracked but rarely affect aggregated statistics.

How We Filter the Raw Data

The Land Registry publishes pp-complete.csv, which covers all of England and Wales from 1995. We apply the following filters to produce our working dataset:

What we do not filter out:

The Land Registry marks each transaction with a PPD Category Type — A (standard) or B (additional, which covers things like new-build developer sales and Right to Buy transactions). We include both categories. Filtering to category A only would remove roughly 20–25% of transactions and produce medians that are systematically higher than the true market. All figures in OpenProp reflect the complete transaction record.

We also apply no price cap. Extreme outliers (e.g. a £50M Mayfair sale) can affect mean prices, which is one reason we default to median rather than mean throughout.

What a "Price" Means Here

Every price figure is drawn directly from the registered sale price at HM Land Registry. This is the completion price — not asking price, not estimated value, not rental yield.

We currently track four price metrics per location, property type, and time period:

Coming soon — Quartile analysis

Lower quartile (LQ), upper quartile (UQ), and IQR are currently in development as standalone query metrics. They are already included in Planning Market Evidence Reports (see below). Full standalone support is coming in a future release.

Why median, not mean?

London's market has extreme outliers at the top end. A handful of £20M sales in Kensington can drag the mean upward significantly. The median is more representative of what a typical buyer actually paid — we use it as the default throughout.

How We Handle Postcode Queries

A London postcode outward code (e.g. SW18) can span multiple boroughs. SW18 straddles both Wandsworth and Merton. We avoid bias with a dedicated postcode dataset computed directly from individual transactions — all sales in SW18 are pooled regardless of which borough they fall in, giving an exact unbiased median for the postcode.

How We Handle Time

We track three time anchors, recomputed on every query:

• Latest complete year — the most recent year with a full 12 months of data (e.g. 2025)

• Latest partial year — the current calendar year, if it has any data yet (e.g. 2026 with January only)

• Latest reliable month — the most recent month where transaction volume has stabilised

Partial-year handling

When the current year has some data, your answer will show two perspectives:

• Fold 1 — Complete years only: e.g. "Last 5 years: 2020 → 2025". All data is final.

• Fold 2 — Up to today: e.g. "Last 5 years: 2021 → 2026". Includes the partial current year as a directional signal, clearly marked with an asterisk (*).

How period phrases are interpreted

Affordability Bands

What We Can Answer

• Median and mean prices for any London borough or postcode

• Min / max prices — cheapest and most expensive sales in a location and period

• Price trends over any period from 2010 to the present

• Growth rankings — which boroughs or postcodes grew fastest over a given period

• New build vs resale price comparisons

• Freehold vs leasehold comparisons

• Transaction volume — how many properties sold in a location and period

• Affordability distribution — share of sales by price band (under £250k, £250k–£500k, etc.)

• Planning Market Evidence Reports — structured price evidence including LQ, IQR, and 5-year trend analysis for planning applications and Financial Viability Assessments

What We Cannot Answer

Geographic scope — We cover Greater London only (all 33 boroughs). No data for Birmingham, Manchester, Edinburgh, or any non-London location.

Time scope — Our data starts from January 2010. Pre-2010 history is not available.

Rental market — We have no rental data. All prices are completed sale prices from the Land Registry. We cannot answer questions about rent, rental yield, or buy-to-let returns. But it is worth to mention I personally believe sale price is a good indicator for the rental price to a large extent. Using the sale price of a property to estimate its rental price is a common practice, but it is not without limitations. The accuracy of this method can vary based on several factors, including the property's condition, location, and local rental market trends. But it is an acceptable proxy generally.

Individual properties — We cannot tell you what a specific address is worth today, or what it last sold for. We report aggregated statistics for areas — not individual property valuations. But this is in my to-do list already, please support us continually to make this happen.

Tenure data gaps — Approximately 30% of Land Registry records lack a freehold/leasehold classification. Tenure comparisons are based on the ~70% of transactions where tenure is recorded.

Sparse data

Some combinations — a specific property type in a small postcode in a specific year — may have fewer than 10 transactions. We always show the transaction count alongside any price figure. A median based on 8 sales is statistically fragile; treat it as indicative, not definitive.

Submission lag — The Land Registry allows up to 2 months for solicitors to register a sale. Very recent months may be revised upward as late registrations arrive.

Borough comparisons — The bot can compare up to 2 boroughs side by side in a single query. If you name more, it will answer for the first two and invite you to ask about the others in a follow-up.

Specific month windows — If you ask about a date range within a year (for example "between February and April 2026"), the answer covers the full calendar year rather than the exact months. We will always tell you which period the answer is based on.

Ready to Start?

The guides below show exactly how to apply these metrics to real decisions:

• First-Time Buyer: Make Your 10 Queries Count — entry prices, lower quartile by borough, avoiding new build traps

• Moving to London for Work: 10 Queries to Pick Your Borough — commute-optimised borough selection

• Rent vs Buy: 10 Queries to Know If Buying Is Actually Possible — deposit timelines, mortgage vs rent comparison

• London's Two-Speed Market: What the 2025 Data Actually Shows — what the aggregate median conceals

Data Licence

All underlying data is sourced from HM Land Registry Price Paid Data, © Crown copyright 2025, licensed under the Open Government Licence v3.0. OpenProp adds the analysis, presentation, and AI-powered interpretation layer on top of this open dataset.