UK HPI Methodology for London

Overview

The UK House Price Index (UK HPI) is the official measure of UK residential property prices, jointly produced by HM Land Registry and ONS. The London series within it is the headline reference for London average price, year-on-year change and first-time buyer values used across PropertyWiki's London cluster.

UK HPI uses completed-sale price data from the four UK land registries, cleaned and combined into a hedonic regression model. The model controls for the changing mix of property types, sizes and geographies selling in any given month, so the published average is comparable over time even when the mix of sales swings.

Methodology at a glance

Sources: GOV.UK About the UK House Price Index; ONS House Price Index QMI; GOV.UK UK HPI England (Feb 2026).

How UK HPI is built — step by step

1. Land registries record completed sales. Solicitors lodge completed sales at HM Land Registry (England & Wales), Registers of Scotland and Land & Property Services (NI). Recording takes a few weeks after legal completion, which is itself usually a few weeks after exchange.
2. Cleaning and exclusions. ONS / HM Land Registry exclude commercial sales, transfers between connected parties and clearly anomalous prices. New-build prices are included once enough transactions accumulate; cash sales and mortgaged sales are both included.
3. Hedonic regression. A hedonic regression model assigns implied prices to property attributes (size, type, location, age) so the index can compare a basket of like properties over time, instead of being moved by a change in the mix of houses that happen to sell.
4. Mix adjustment and weighting. Modelled prices are then weighted by the standard property mix to produce an average price for each geography. For London this prevents a heavy month of central flat sales (or a quiet month of family-house sales) from distorting the published average.
5. Borough smoothing. Borough-level series apply a three-month moving average to reduce the impact of small monthly samples. Single monthly movements at borough level should always be read as directional rather than precise.
6. Publication and revision. UK HPI publishes monthly via the GOV.UK statistical bulletin and the UK HPI data service. Each release revises earlier months as more land-registry data arrives, so historical figures can move slightly between releases.

PropertyWiki editorial rules

We apply the following rules across every London borough page so UK HPI figures are presented consistently and never overstate precision.

• — Always quote the reference month (e.g. February 2026), not the publication month, and label values as provisional when they are inside the typical revision window.
• — Treat single-month borough movements as directional only — compare against the rolling 6- and 12-month change for the same borough before drawing conclusions.
• — Never compare a UK HPI sold-price figure with a portal asking-price figure. They measure different things at different points in the transaction lifecycle.