I analysed 63,973 London property sales. Here's what nobody tells first-time buyers.

On the latest twelve months of sales across 50 neighbourhoods, 208 pairs show the same inversion: the area with the lower headline price has the more expensive flats and the more expensive terraced houses.

When I started this analysis, the first pattern I noticed was an odd pair on the south-east side of the map. Crystal Palace, the area built around the Victorian park and the broadcast mast, looked cheaper than nearby Catford. The median sold price in Crystal Palace was £40,000 below Catford's. On any property portal, Crystal Palace was the budget-friendlier option.

Then I looked at the flats.

The median sold flat in Crystal Palace cost £35,000 more than the median sold flat in Catford. The median terraced house in Crystal Palace cost £39,250 more. The cheaper neighbourhood was, on the actual properties you would buy, the more expensive one.

That seemed strange enough that I checked whether it lasts. It does — the same inversion was there in the original three-year study window, and it is still there on the most recent twelve months of sales. The headline says Crystal Palace is cheaper; the flats and the terraces say the opposite. Same direction, two windows apart.

The sharpest example sits closer to the first-time-buyer price band. Hither Green in Zone 3 has a median sold price of £450,000. Ilford, the larger area a few miles east in Zone 4, sits at £508,500. A first-time buyer scanning by headline price would conclude Hither Green is the £58,500 saving. They would be looking at the wrong number. The median flat in Hither Green costs £108,750 more than the median flat in Ilford — about 42% more. A buyer who picks Hither Green over Ilford to save £58,500 on the headline is, on the flat they'd actually buy, paying about £108,750 more.

There is a simple reason this happens. A neighbourhood's headline figure is a blend across every type of property sold in the area. If two areas have very different property mixes — one heavy on small ex-local-authority flats, one heavy on larger Victorian terraces — the headline will sort by mix, not by property. The number on the portal is comparing what the area happens to contain, not what the area actually charges for what you are buying.

A first-time buyer is not buying a property mix. A first-time buyer is buying one specific flat, or one specific terrace. The number that matters is the median for that property type. The area headline is, in most cases, a misleading proxy for the only number you should care about.

Same Zone 4 area. About £107,000 difference in headline price. Thirty minutes' difference each way on the commute. Every working day.

The Tube map is a Tube map. It is not a commute map. The fastest way to learn this is to look at peak journey times to the City from London neighbourhoods in the same fare zone.

Barking sits in Zone 4. The median sold price is £343,231 — among the cheapest in the entire dataset. The peak journey time from Barking to Bank station on the District Line is 34 minutes, with three changes.

Hounslow also sits in Zone 4. The median sold price is £450,000. The peak journey time from Hounslow to Bank on the Piccadilly Line is 64 minutes, with two changes.

Same zone. £106,769 difference in sticker price. Thirty minutes' difference each way on the commute. Sixty minutes a day. Five hours a week, fifty weeks a year — the better part of a working week, every year, for as long as you live there.

The pattern repeats inside the more central zones too. Stratford and Brixton both sit in Zone 2. Stratford reaches Bank in 25 peak minutes for a median sold price of £445,500. Brixton reaches Bank in 33 peak minutes for £510,000. Same zone, Brixton is eight minutes slower and £64,500 more — yet "Brixton" reads to most people as the more central, more obvious choice. Once you stop using zone as the proxy, the actual numbers tell a different story.

Zones are radial. They are circles, drawn from Charing Cross outwards, that determine your fare. The rail lines that actually carry you to work are not radial. They follow nineteenth-century alignments and post-war extensions and the Elizabeth Line's east-west sweep across the city. A direct line from a Zone 4 station to a Zone 1 hub is often faster than a two-change Zone 3 trip. Zone is a fare concept; commute is a line concept; nobody markets the second one because the first one is on every map.

The single most actionable lesson I would take from this is that any buyer using "low zone number" as a proxy for "short commute" is buying the wrong proxy. The number to look at is the peak journey to wherever you actually work.

While we are here: a Zone 3 area called Upton Park reaches Bank in 29 minutes for a median price of £396,300. Walthamstow, the same zone, reaches Bank in 43 minutes for £570,000. Upton Park is faster by a quarter of an hour, and £173,700 cheaper. I do not know how many buyers would draw that comparison in their first month of research. I did not, before I ran the numbers.

Hounslow Central records 371.8 crimes per 1,000 residents. Hounslow South records 51.9. The same area name, 7.2× apart.

Of every question a first-time buyer asks about an area, the most anxious one is "is it safe?" The way Google answers that question is by serving up a single number — a crime rate per thousand residents, or a colour-coded map, or a one-line verdict. The way the data actually answers it is much more interesting.

Almost every London neighbourhood has wards inside it that differ from each other by a wide margin. Crime is not evenly spread across an area. It clusters — where the footfall is, where the night-time economy is, where the transport hubs and the shopping centres are. The streets two minutes from those clusters can carry a fraction of the recorded crime; the streets two minutes the other way, a multiple of it.

The area-level crime rate for Hounslow is 140.6 per thousand, modestly above the London average of 128.9. That looks like a tolerable middle-of-the-pack number. Inside Hounslow, the Hounslow Central ward records 371.8 per thousand. The Hounslow South ward, fifteen minutes' walk away, records 51.9. Both wards are inside the same area name. Both feed into the same Rightmove "Hounslow" listing. The estate agent will quote you the area number. Neither ward is the area number.

The pattern repeats. Wood Green has a ward 3.5 times worse than its quietest; Croydon 3.7 times; Romford 3.2 times. Across the areas analysed, ward-to-ward gaps of roughly two to seven times are routine, with Hounslow's 7.2× the widest. One caution in the reader's favour: these are full-ward rates, and the gap between individual streets is wider still — so the figure to trust is always the one for the exact postcode, not the area or even the ward.

Stratford deserves a paragraph of its own here. The area's top-line crime score looks alarming, and it drives a lot of bounced shortlists. Most of that score is theft — 4,820 recorded cases — concentrated at Westfield, the Stratford Centre, and the rail and Underground stations. Pickpocketing at a regional shopping mall is a real risk, but it is not what most buyers are asking about when they ask whether Stratford is safe. The people who live in residential Stratford, three streets from the shopping centre, experience an entirely different crime profile from the one the area average implies.

The right question is not "is this area safe?" The right question is "which streets in this area, and what kind of crime, and at what time of day?" data.police.uk lets you ask that question by postcode. It takes three minutes per area. The next time you find yourself afraid of a number on a property portal, that is the three minutes I would spend.