The official reading

The UK House Price Index for July 2026, published by HM Land Registry and the Office for National Statistics on 16 September, put the average UK home at £273,000 — 1.4% higher than a year earlier — and the average London home at £550,037, which is 3.3% lower. The release is explicit that this is the eleventh consecutive month in which London's annual rate has been negative, and the lowest annual rate for the capital since January 2024. Inner London carried the heaviest weight. The North East, at +4.9%, was the fastest English region, and the UK's annual rate slowed for a third month, from a revised 1.5% to 1.4%.

Two sentences in that release decide whether a prime buyer should read it at all. The first: London was the English region with the lowest annual inflation. The second: flats are the drag. Both are true of a register that measures the whole market, which is not the same thing as a market for £5m flats.

Twelve months of the split

The release's headline table gives one number per region. The dataset underneath it gives the property-type detail by month, and that is where the London story is legible. This desk pulled the London region series (area code E12000007) from the UK HPI full file published with the July release and built the series below. Each line is the annual change in the twelve months to that month, for London, by property type.

  • Aug 2025 — all +0.2%, flats −1.5%, semi-detached +2.3%, detached +0.5%, terraced +2.0%
  • Sep 2025 — all −0.1%, flats −1.1%, semi-detached +0.6%, detached −0.9%, terraced +1.4%
  • Oct 2025 — all −0.6%, flats −2.4%, semi-detached +1.6%, detached +0.4%, terraced +1.4%
  • Nov 2025 — all −0.3%, flats −2.4%, semi-detached +2.1%, detached +0.5%, terraced +2.3%
  • Dec 2025 — all −1.5%, flats −4.1%, semi-detached +2.2%, detached +0.5%, terraced +1.0%
  • Jan 2026 — all −1.8%, flats −3.9%, semi-detached +0.3%, detached −1.4%, terraced +0.7%
  • Feb 2026 — all −2.7%, flats −4.8%, semi-detached +0.2%, detached −0.4%, terraced −0.7%
  • Mar 2026 — all −1.3%, flats −4.6%, semi-detached +3.0%, detached +3.1%, terraced +2.0%
  • Apr 2026 — all −2.1%, flats −4.4%, semi-detached +0.4%, detached −2.0%, terraced +0.8%
  • May 2026 — all −3.1%, flats −5.8%, semi-detached +0.4%, detached −1.9%, terraced −0.1%
  • Jun 2026 — all −3.1%, flats −5.6%, semi-detached +0.3%, detached −1.0%, terraced −0.5%
  • Jul 2026 — all −3.3%, flats −6.6%, semi-detached +1.1%, detached +1.2%, terraced −0.2%

Source: HM Land Registry, UK House Price Index full file, July 2026 release (16 September 2026); desk extraction of the London regional series.

In pounds, London's average flat went from £454,151 in July 2025 to £424,013 in July 2026 — £30,138, or 6.6%. Semi-detached houses moved the other way, up 1.1% to £724,106. The spread between the two is 7.7 percentage points, the widest in the twelve months shown, against 3.8 points a year earlier. The same shape, milder, appears nationally: the release's own property-type table has UK flats at −2.4% and semi-detached at +2.9%.

What the index cannot see

The UK HPI is a register, not a valuation. It reads completed sales registered with HM Land Registry for England and Wales, Registers of Scotland and, quarterly, Northern Ireland's Land & Property Services — cash sales and mortgaged sales alike, down to individual addresses. That is a strength when you want the whole market, and a limitation when you own one expensive flat in it.

HM Land Registry's own methodology sets out the exclusions, and one of them matters here. Sales of residential property where the buyer or the seller is a corporate body, company or business are excluded from the Land Registry data used in the UK HPI; the methodology notes that Scotland's Registers of Scotland dataset does include them. A £5m Westminster flat held through a company, or bought from one, is therefore not in the London sample at all. Nor is a sale that is not at full market value, or a sale of a share in a property. The −3.3% is a statement about the properties the index can see, and the region's average of £550,037 is dominated by ordinary stock, not by the top of the market.

So the official read tells a prime buyer two things: how the broad London market is doing, and — more usefully — which half of it is doing worse. It does not price the flat. For that side, Knight Frank's public prime London research (4 September) has average prices in prime central London down 3.3% in the year to August and 23% lower than eleven years ago, with prime outer London off 0.4%. Different survey, same direction.

The rent side is the actionable half

The Office for National Statistics, publishing the same day, put the average UK monthly private rent at £1,400 in August 2026, up 3.8% in twelve months — the highest annual rate since December 2025. The ONS attributes the rise mainly to London, where annual rent inflation climbed to 3.5% from 3.0% in July, on an average rent of £2,332 a month, the highest of any English region against £788 in the North East.

Knight Frank's prime lettings read, also 4 September, says the pressure is supply. New listings across prime central and prime outer London ran 10% below the five-year average in the three months to August, and tenancies agreed fell 8% on the year — the same 8% as the fall in supply. Rents rose 3% in prime outer London and 1.2% in prime central. In prime outer London there were 8.7 new prospective tenants for every new listing in August, a five-year high, against 5.2 in prime central.

Independent of both, e.surv's GB index (published 8 September) has annual growth at 1.8% with semi-detached and terraced houses leading and Scotland the exception to the weaker trend for flats — evidence that the flat-versus-house split is a national pattern rather than a London quirk.

What this does to a Hong Kong landlord's arithmetic

For the Hong Kong family holding a London flat, the two official lines move in opposite directions, and that is the whole point. On the index's own London flat series the capital line fell 6.6% over the year; on the ONS London series the rent line rose 3.5%. Apply the first rate to £5m and the capital movement is £330,000 in twelve months. Annualise the second — £2,332 a month is £27,984 a year — and the official London average rent is 0.56% of £5m, which tells you the official rent average describes the ordinary London flat, not this one. Knight Frank's super-prime lettings bracket, which it sets above £5,000 per week, had 13% more tenancies in the three months to August than its five-year average.

Two practical consequences. The income is being repaired while the capital is being marked down: a landlord whose rent is indexed to the market is collecting more each year on an asset that is worth less, which is what a higher gross yield on cost looks like from the inside. And the flat-versus-house split is not noise — a flat owner is on the weak side of the only split the official data bothers to publish. Sterling is the third variable: the rent is sterling income, and the desk's ticker carried the pound at GBP/USD 1.3344 at 07:15 HKT on 20 September, so the Hong Kong-dollar value of that rent moves with the currency as well as with the rent.

The date to watch

The next reading is a fixed one: the August 2026 UK House Price Index is published at 9.30am on Wednesday 21 October 2026, per the release's own calendar. That is the number that will show whether London's flat series has closed any of its 7.7-point gap on semi-detached houses — or widened it a fourth quarter running. Knight Frank's Tom Bill notes a Budget on 28 October, seven weeks after his note, with pre-Budget speculation already showing up in how buyers negotiate rather than whether they walk.

One month of data will not settle that. But the composition will: if the August release shows London rents still climbing while flats keep underperforming houses, the official data will be saying something unusually clear about where the value is — and it will be saying it about the half of the market that a company-held prime flat is not in. A reader who wants the other side of this, and how the prime cycle differs from the register, can start with what 'prime' means when rates stay honest, then London prime after the non-dom era, and for the London-versus-Dubai comparison in Chinese, 倫敦與杜拜的頂級住宅：同一個周期，兩種地板.