ONS House Price Figures Face Accuracy Questions as Market Weakens
The accuracy of official UK house price data is under fresh scrutiny after analysis revealed that the Office for National Statistics (ONS) has consistently revised down its monthly house price growth figures over the past two years. According to a report published this week, every ONS monthly data release for the UK-wide property market has been revised lower 12 months later, raising concerns that inflated figures are distorting expectations among buyers, sellers, and estate agents.
The latest ONS data had shown a modest 0.9% rise to £273,000 in the year to August 2026. However, the pattern of downward revisions suggests the true picture may be considerably weaker. In one example cited, average house prices in Dacorum, Hertfordshire, for December 2024 were first reported at £423,396 in February 2025. By September 2026, that figure had been revised down to £406,468—a full 4% lower than initially stated. The ONS has acknowledged methodological changes late last year that wiped tens of thousands of pounds off historic figures, though it admitted the new methodology has not yet been applied to all local data.
RICS Survey Points to Sharp Slowdown
The accuracy concerns come as the Royal Institution of Chartered Surveyors (RICS) reported its most downbeat outlook for house sales in more than three years. In its October survey, a net balance of 17% of property professionals expect sales to fall over the next 12 months—the weakest reading since July 2023. The headline house price balance dropped to -36 from September's revised -34, exceeding economists' forecasts. New buyer inquiries remained at a net balance of -24, unchanged from September, with nearly all parts of the UK experiencing falling or stagnant demand. Agreed sales also slipped to -24, the weakest in three months.
RICS head of market research Tarrant Parsons said: "Home buyer demand remains subdued and respondents are bracing for a weaker year ahead for sales given the persistent macroeconomic challenges being faced." The survey follows the Bank of England's decision last week to raise interest rates to 4% from 3.75%, its first hike in three years, further squeezing mortgage affordability.
Context: Overvalued Listings and Stalled Sales
The discrepancy between official data and market reality has tangible consequences. Charlie Lamdin, who runs estate agent network BestAgent, said: "Home-movers and estate agents accept the ONS's report without question. But it's problematic because they see house prices going up by X per cent, and then wonder why their house isn't selling."
Nearly half of all homes listed in the last three years failed to reach a sale, according to property portal Zoopla, with more than a third of homeowners who didn't sell admitting the asking price was "too high." Those who did sell took an average hit of 3.5% below the original asking price—equivalent to an £18,800 reduction. Richard Donnell, who compiled Zoopla's analysis, noted that over-optimistic valuations are one of the biggest barriers to a quick sale, with around 50% of homes listed failing to find a buyer within six months.
The weakness is particularly pronounced in London's prime property market. In the capital's zone 1, there were 1,400 completed but unsold homes at the end of September—three times the number recorded in 2016, according to researcher Molior. Just 1,600 homes started construction in the area in the past 12 months, 75% fewer than a decade ago. Developers are feeling the strain: London Richmond, a specialist developer with a portfolio of 20 properties worth over £30m, appointed administrators in August, leaving more than 300 creditors awaiting £39m in remaining debt.
Perspective: A Market Adjusting to New Realities
The combined picture suggests a housing market that is weaker than headline figures imply. While prices continued to rise firmly in Northern Ireland and modest growth was reported in Scotland and the North West of England, London, East Anglia, the West Midlands, and the South East recorded weaker price trends than the general average. Property professionals also revised down their price expectations for the year ahead, with a net balance of 17% now expecting falls, deteriorating from a flat reading previously.
The rental market offers a contrasting trend: tenant demand saw modest growth while landlord instructions continued falling, pushing expectations for rent growth over the next three months to +41, the strongest since early 2024. This divergence highlights how higher borrowing costs are reshaping the property landscape, potentially pushing more people into renting while dampening sales activity.
As the ONS works to apply its revised methodology across all local house price figures, the gap between official statistics and on-the-ground experience may narrow. But for now, the data suggests that the UK housing market is entering a cooler phase, with buyers and sellers alike grappling with affordability constraints and uncertain price signals. The RICS survey indicates that the sales outlook is the darkest since 2023, and with interest rates rising again, the pressure on the market shows little sign of easing.
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