Most of the best homes in prime central London sell without ever being advertised. How off-market deals happen, why sellers prefer them and how a buyer gets in.
By Aldo Attanasio d’Aponte – September 9, 2026
Off-market property in London: how buyers get access to unadvertised homes
In prime central London the property portals show you the market’s second tier. The best houses and the best lateral flats are usually agreed before a photographer has been booked, between a seller who values privacy and a buyer whose adviser was told first. Getting access to that layer is not a trick; it is the product of relationships, credibility and a great deal of unglamorous work.
What does “off-market” actually mean?
The term covers several different situations, and it helps to separate them. There is the genuinely private sale, where an owner has decided to sell but will only see one or two introduced buyers. There is the pre-market instruction, where an agent has been appointed and is quietly testing the price with buying agents before the listing goes live. There is the withdrawn property, taken off the portals after a failed sale but still available at the right number. And there is the home that is not for sale at all until someone asks.
That last category is the one I find most interesting. For example, we secured 16 Old Bond Street for Prada. It was not for sale. We identified the overseas owner, made a direct and discreet approach, and assembled it with the neighbouring buildings the brand already held into a single flagship. The same method works for a house on a garden square. Of the residential purchases we have advised on since 2006, 78% were secured off-market, and a meaningful share of those began as a letter to an owner who had not thought about selling.
Why do sellers in prime London avoid advertising?
Privacy comes first. Owners of significant houses do not want floor plans, security arrangements and photographs of their children’s bedrooms available to anyone with a browser. Nor do they want neighbours, business partners or the press drawing conclusions from a listing. A quiet sale to a vetted buyer removes all of that.
Control comes second. A public listing invites dozens of viewings from people who are curious rather than able. An introduced buyer arrives with proof of funds already checked and a clear brief, which is a better use of the seller’s time and often of their patience.
Price comes third, and this is where buyers should pay attention. Some sellers go off-market because they want a premium for discretion. Others go off-market because they would rather not have a visible reduction on the portals if the first price is wrong. The buyer’s adviser has to work out which seller they are dealing with, because the negotiation is different in each case.
How do buyers find off-market homes?
You cannot search for what is not listed. The practical route is a network of people who hear about sales before they happen: selling agents at every level of the market, from the international names to the one-office firms who have handled the same square for thirty years; solicitors and private bankers whose clients mention a move; developers; and owners themselves, approached directly when a building fits a brief.
London’s agency market is extremely fragmented. There are hundreds of firms operating in the central postcodes alone, and much of the real information now moves in private messaging groups rather than on any website. A private buyer cannot maintain those relationships from abroad, or even from an office in the City. That is the job of a buying agent, and it is why the good ones are the first call when a seller wants a quiet exit.
Credibility is the other half of access. A selling agent will show a private house to a buyer introduced by a firm whose clients have completed reliably for twenty years, and will not show it to an anonymous enquirer. When we put a client forward we are vouching for them, which is why we are careful about who we act for.
How is an off-market deal negotiated?
Without a listing there is no asking price to anchor to, which cuts both ways. The seller may float a number that reflects hope rather than evidence. The buyer’s job is to establish what the property is worth on comparable transactions, including the ones that never appeared online, and to make an offer that is credible on the first approach. On average our clients pay 12% below the initial asking figure, and off-market deals are where that discipline matters most, because there is no public pricing to correct a seller’s expectations.
Understanding the seller matters as much as the numbers. Why are they selling, what is their timetable, is there a probate, a divorce, a move abroad or a tax deadline behind the decision? Each of those changes what a good offer looks like. Sometimes the right answer is speed and certainty at a fair price; sometimes it is patience. I have told clients to wait on more than one occasion, and it has cost us a fee and been the right advice.
Due diligence does not get lighter because the deal is discreet. If anything it is heavier, because there has been no marketing period during which problems surface. Survey, title, lease terms, planning history, service charge accounts and any building safety issues all need to be examined before exchange, and a buyer who has been offered exclusivity should use it to do that work properly rather than rush.
What are the risks of buying off-market?
The main one is overpaying for the privilege. “Off-market” has become a marketing phrase, and some sellers and agents use it to suggest scarcity where there is none. A buyer should ask why this property is being sold quietly and whether the price reflects a discount for a fast, private sale or a premium for exclusivity.
The second risk is buying in isolation. Without seeing the wider market a buyer can convince themselves that the one house they were shown is the one. A good adviser will still map the whole market, on and off, so that the private opportunity is judged against everything else.
The third is confidentiality. If a client’s interest leaks, the price rises and the seller’s goodwill falls. We work with a small number of high-profile clients whose names never appear on an offer letter, and that discipline applies to every client, not only the famous ones.
How Arbitrage can help
We act only for buyers and have been securing homes in prime central London since 2006, most of them before they were advertised. We know which agents, owners and buildings to approach, and our clients are taken seriously because we have completed reliably for twenty years. If the right house is not for sale, we will ask.
Frequently asked questions
What proportion of prime London homes sell off-market?
At the top of the market a majority of houses and the best flats change hands without a public listing, and the proportion rises with price. Our own figure is 78% of the purchases we have advised on. Below around £2m the open market is still the main route.
Is an off-market property cheaper?
Not automatically. Some private sales are priced attractively because the seller wants speed and discretion; others carry a premium. The only protection is independent evidence of value and an adviser who is paid by you, not the seller.
Can I approach an owner directly myself?
You can, and occasionally it works. In practice owners respond better to an approach from an established firm acting for a named, vetted buyer, because it signals seriousness and does not oblige them to deal with a stranger. The letter is the easy part; the follow-up is the work.
Do I need a buying agent to access off-market homes?
Not in theory, but in practice the information moves through a network of agents, lawyers and bankers that a private buyer cannot maintain. A buying agent with a long track record is the point of entry, and their fee is only paid if a purchase completes.