THE PROPERTY FILTER TAKE
Gaffon's data puts London flats at £6,639 per square metre, below the £6,787 of 2017, while terraced houses rose 40.2% over the decade to 2025.
In practice this means London flats as a whole have made no cash gain per square metre since 2017 on this measure, before inflation.
Consider re-testing the rental yield on any London flat you hold or plan to buy, rather than relying on capital growth.
London flat values are now lower per square metre than they were in 2017. Flats sell for £6,639 per square metre, against £6,787 nine years ago, according to Gaffon's borough-by-borough square metre analysis. That is a cash fall of £148 per square metre, which Gaffon puts at 2.2%. PropertyWire reported the findings on 29 September 2026.
How far have London flat values fallen?
Gaffon, a video property listings platform, matched 1,091,977 Land Registry sales to their Energy Performance Certificates (EPCs, the energy rating documents that record a home's floor area). It then priced each sale per square metre. Gaffon says this measure corrects for the mix of homes sold in any one year.
That matters because a median price (the middle price of all sales) can swing on mix alone. If cheaper homes do more of the selling, the median falls without any home losing value. Gaffon argues the square metre strips that effect out.
On that measure, Gaffon says flats "stalled first and longest". Terraced houses went the other way, up 40.2% from £4,639 to £6,502 per square metre by 2025, in what Gaffon calls "the decade's work". Gaffon does not state the start year of that rise; its chart runs from 2015.
Across all London homes, Gaffon's square metre price peaked in 2022 at £6,664. It then moved just 0.6% in total over three years. In 2026 so far it has dipped 3.9% from 2025's £6,624 to £6,364, the first cash dip in the series, Gaffon says. Gaffon notes 2026 is year to date and the register lags completions.
Which London boroughs are affected most?
PropertyWire reports that Kensington and Chelsea saw the steepest decline, a 26% fall from a 2018 peak. Gaffon's own table shows that figure is the borough's median price, down 26.0% from £1.43m in 2018. Per square metre, Kensington and Chelsea is down 13.0% from its peak, Gaffon says. On that measure Westminster is furthest below its peak at 19.3%, then Tower Hamlets at 14.2%.
Waltham Forest is the only borough currently at a per square metre record, up 2.0% on its best previous calendar year, according to Gaffon. Its borough table covers the last 12 months, July 2025 to June 2026.
Gaffon also compares median prices by property type in its four strongest boroughs, 2019 against the last 12 months. These are Waltham Forest, Barking and Dagenham, Bromley and Redbridge. Terraced and semi-detached houses there rose 18% to 32%, which Gaffon summarises as 20% to 32%. Flats rose 1% to 5%, with one exception Gaffon flags: Redbridge flats up 15%, off a low base. In Barking and Dagenham, the median flat went from £233,000 to £235,000. The median terraced house went from £325,000 to £400,000. These are medians, not square metre prices.
New-build homes made up 3% or less of sales in those boroughs. Gaffon reads this as existing family houses repricing, not new developments. If you are weighing specific postcodes, you may wish to run area checks with Property Filter's deal-sourcing software.
Note the different starting points. The flat figure runs from 2017, the Kensington and Chelsea median peak from 2018 and the borough type comparison from 2019. They are separate periods and do not compare directly.
What does this mean for flat investors in practice?
Inflation is the part the cash figures hide. Gaffon says London prices have been flat in cash since 2022, with roughly 20% inflation over that time. It estimates that means roughly a fifth of real value has gone. That estimate covers London homes overall, not flats alone.
PropertyWire notes that government schemes target first-time buyers, who typically enter the market through flats. It says the divergence between property types may influence investment strategies.
Who is affected? Owners of London flats bought since 2017, and investors choosing between flats and houses in the capital. Our reading, which is analysis rather than a finding of the data, is that flat returns now lean on rent more than growth.
If that describes your holding, consider checking the numbers with our free buy-to-let stress test calculator. It shows whether the rent covers a lender's stressed mortgage test.
For the wider choice between flats and houses, our property investment strategies hub collects our guides to the main strategies, from buy-to-let to HMOs (houses in multiple occupation).
Key takeaways
London flats sell for £6,639 per square metre, against £6,787 in 2017, a cash fall of 2.2% (Gaffon).
Terraced houses rose 40.2% to £6,502 per square metre by 2025, over what Gaffon calls the decade.
Kensington and Chelsea's 26% fall is a median price figure; per square metre it is down 13.0% from its peak (Gaffon).
Waltham Forest is the only London borough at a per square metre record, up 2.0% (Gaffon).
Gaffon estimates roughly 20% inflation since 2022 has eroded real London values while cash prices stayed flat.
Frequently asked questions
Are London flat prices lower than in 2017?
Which London borough has fallen the most?
Where in London are prices still rising?
