How to find what other flats in the same building sold for

An asking price is a hope. A sold price is a fact. If you're looking at a flat, the most useful comparison you can find is usually another flat in the same building, because it shares the same address, the same lease issues, the same service charge setup and the same street noise.

The good news is that this information is public. HM Land Registry publishes what properties in England and Wales sold for, and you can search it for free. It won't tell you everything, but it gives you a far firmer footing than an estate agent's say so.

The official source is the HM Land Registry price paid data on gov.uk. You can search by postcode, street or town, and the results list the sale price, the sale date, the full address (including the flat number) and the property type.

Several property websites reuse this same data and present it with maps and filters. They can be quicker to browse, but they're repeating the official records, so if a figure looks odd, check it at source.

One thing to know. This is not the same as the Land Registry's free property search, which only tells you whether a property is freehold or leasehold and gives its title number. Price paid data is a separate service, and it's the one you want here.

Here's a simple routine that works for most blocks.

1. 1Search by the full postcode of the building, or by the street name if the postcode covers lots of properties.
2. 2Filter to flats if the tool lets you, so houses nearby don't muddy the picture.
3. 3Look for entries with the same building name or street number, then note each flat number, sale date and price.
4. 4Sort by date so you can see the newest sales first.
5. 5Write the results into a simple list, with the flat number, floor if you know it, price and date.

If the block has a name rather than a number, try both. Records can be entered in slightly different ways, so a search for the name and a search for the street number may turn up different entries.

This is where people get carried away. A neighbour's price is a clue, not a valuation. Before you treat it as a benchmark, ask yourself a few honest questions.

How old is the sale? A price from several years ago reflects the market and the lease at that time. It may be a poor guide now.

How does the flat compare? Floor, aspect, size, condition, balcony, parking and views can all move a price. A refurbished top floor flat and a tired ground floor one are not twins just because they share a front door.

What about the lease? This matters a lot. A flat with a long lease will usually be worth more than an otherwise identical one with a short lease. Lenders commonly want around 70 to 85 years left when you apply and 30 to 40 years left when the mortgage ends, and each lender sets its own figure. So a flat that sold with a short lease may be a weak comparison for one with a long lease, and the other way round.

Was it a normal sale? Price paid data generally records the price, but it doesn't explain the story behind it. A quick sale, a sale between relatives or a sale of a flat in poor repair can all look unusual. Treat outliers with caution rather than ignoring or leaning on them.

Price paid records are useful, but they have gaps. They won't show the condition of the flat, the number of bedrooms, the service charge, the ground rent or the remaining lease length. They also lag behind the market, because a sale only appears after it completes and is registered. Very recent deals may not show up yet.

If you want the lease detail behind a sale, you can pay 7 pounds on gov.uk to download the title register, the title plan or a copy of the filed lease for a property. That can help you see what a neighbouring flat was actually sold with, though you should be careful about how you use it and how current it is.

And don't forget that asking prices aren't recorded here at all. Only completed sales are.

Once you have your list, look for a pattern rather than a single number. If three similar flats sold within a fairly tight range, that's a decent signal. If the prices are all over the place, work out why before you lean on any of them.

Then put it alongside the rest of your research. Check current listings in the same block, ask the agent which recent sales they think are comparable, and get your solicitor to look closely at the lease, service charge and any planned major works. Lease law is changing in places, and some reforms are not yet in force, so confirm anything lease related with a solicitor rather than assuming.

Used properly, the sold prices won't win you a bargain on their own. But they will stop you overpaying by guesswork, and that's worth the half hour it takes.