The buying mistakes that cost buyers in London most: arriving unprepared, the wrong survey, underestimating works, overpaying on emotion; how to avoid them.

By Aldo Attanasio d’Aponte – September 9, 2026

The most expensive mistakes buyers make in London, and how to avoid them

Most of the money lost in a London property purchase is lost before the offer is made, in preparation that did not happen and questions that were not asked. Prime central London is an expensive place to learn by experience. After twenty years on the buyer’s side of the table, the same handful of errors account for nearly every regret I have heard from a client, and every one of them is avoidable.

Are you actually ready to buy?

The first mistake is viewing before you can transact. In this market the best properties, particularly the ones sold before they are advertised, go to the buyer who can move, and a seller’s agent forms a view of you within one conversation. Proof of funds, a mortgage offer or a private bank’s confirmed facility, a solicitor already instructed and identity checks already passed are not administrative details; they are your negotiating position.

Being unready costs money in a direct way too. A buyer who finds the right house and then spends three weeks arranging finance gives the seller three weeks to find someone else, or to raise the price. We do not begin viewing for a client until the funding, the legal team and the ownership structure are settled, and I would say that a week spent on this at the start saves a month, and often a good deal more, at the end.

Have you chosen the right professionals?

The second mistake is economising on the people who protect you. A conveyancing solicitor is not a commodity. A cheap volume practice may take six weeks to raise enquiries that a specialist prime London firm raises in six days, and in a competitive situation that delay is the deal. Use a firm that knows leasehold, that has seen the freeholder’s standard lease before, and that will pick up the phone.

The same applies to the surveyor. A general building survey is right for a Victorian terrace. A lateral flat in a serviced building with lifts, air conditioning, a plant room and a pool needs specialist mechanical and electrical reports as well, because those systems are where the six-figure surprises hide. A house with a basement needs a structural engineer. Choose the survey for the property, not for the price.

Is the survey enough?

Which leads to the third mistake: assuming the survey you have covers what you need. A mortgage valuation is not a survey; it is the lender protecting itself. A mid-level report is a visual inspection with caveats. Only a full building survey, RICS Level 3 or the equivalent, involves the surveyor looking properly at the structure, the roof, the services and the damp, and even then it describes what can be seen, not what is behind the plaster.

For any property with age, alterations or a basement, commission the full survey and read it yourself. Then ask the surveyor the question a report never quite answers: “If this were your money, what would you want to know before exchange?”

Have you priced the work?

The fourth mistake is underestimating what the property will cost after completion. Unmodernised houses in prime London are frequently priced only a little below finished ones, so the discount for taking on the works can be illusory, and the works themselves cost more than any first estimate. A realistic budget for a full refurbishment of a period house includes VAT, professional fees, a contingency of at least 15%, and the rent or lost income for the eighteen months you are not living there.

We build houses ourselves, from Park Street in Mayfair to Lexham Gardens in Kensington, so we cost a client’s works before an offer goes in, and we check the planning history and the listing status at the same time. A plan that depends on a rear extension the conservation officer will refuse is not a plan. Beyond refurbishment, high stamp duty means buyers now move less often, so ask whether the property will still suit you in ten years. The cost of moving twice is the most easily avoided cost in London property.

Did you look properly?

The fifth mistake is the rushed viewing. Twenty minutes with a selling agent who has the next appointment waiting is not an inspection. Go back, at a different time of day, and look at the things that are not in the brochure: the noise at 7am, the light at 4pm in winter, the state of the common parts, the parking, the neighbours’ extensions, the drains. Open the windows. Run the taps. Ask who lives above and below.

If the agent hurries you, ask why. An agent with a sound property and a serious seller is content to let a buyer take their time.

Have you checked the location, not just the property?

The sixth mistake is buying the right house in the wrong place. Location is the one thing a purchase cannot change. That means the specific street, not the district: which side, which end, how close to the main road or the pub or the school gate, what the council’s plans are for the road, what the neighbouring site is consented for. A quiet garden square in Kensington and a street two hundred metres away that carries the traffic to the A4 are both “Kensington”. They are not the same purchase.

Your own priorities decide what matters, but be honest about them. A buyer who will always drive can discount the tube; a family with children at school in Barnes cannot discount the school run.

Are you buying with your head?

The last mistake is the one that causes the others: falling for a property and letting the seller’s agent know it. Every agent is trained to detect this, and once detected it is used. A buyer who is visibly in love does not get the discount, does not get the fixtures thrown in, and does not get the seller’s cooperation when the survey turns something up.

This is one of the quieter reasons to use an adviser on your side. We are the layer between the client’s enthusiasm and the seller’s agent, and the price we negotiate reflects the property, not the feeling. It also means we can tell a client to walk away, or to wait, without any awkwardness. That advice sometimes costs us a fee. It is often the most valuable thing we do.

How Arbitrage can help

We act only for buyers, and we prepare a client before the first viewing: funding, structure, legal and tax advisers all in place, so that when the right property appears we can move and negotiate from strength. On average we secure property 12% below asking, and 78% of what we buy never reaches the open market.

Frequently asked questions

What is the single biggest mistake London buyers make?

Overpaying because the seller’s agent could see how much they wanted the property. Everything else on this list, from poor preparation to skipping the second viewing, tends to feed into that one outcome. An independent adviser between you and the selling agent removes it.

Do I have to use the solicitor the estate agent recommends?

No, and it is usually better not to. The agent’s referral is a commercial arrangement, and the agent’s interest is the seller’s. Choose a firm with a track record in the kind of property you are buying, particularly for leasehold flats in prime London.

Which survey should I get for a London flat?

A full RICS Level 3 building survey at minimum, and for flats in serviced buildings a separate mechanical and electrical inspection covering lifts, air conditioning and plant. Ask your solicitor to obtain the block’s service charge accounts and reserve fund at the same time; a survey of the flat tells you nothing about the building’s finances.

How much contingency should I allow for refurbishment?

At least 15% on top of the contractor’s price, plus VAT and professional fees, and more for listed buildings. Period London houses reliably conceal problems that only appear once the walls are opened.