Where London's green space actually is

Roughly a fifth of Greater London is public green space, which is genuinely unusual for a city this size. It is also an average, and averages are where useful information goes to die.

Measure the green space within a mile of the average postcode in each borough:

Richmond upon Thames records 166 hectares (1st highest of 33) against Islington records 54 hectares. Same city, three times the greenery.

Now count the parks instead of the hectares

Here is where it gets genuinely surprising. Measure the number of distinct green spaces within a mile instead of their total area, and the table turns almost upside down:

Islington is 32nd of 33 on hectares and 1st on the number of green spaces. Havering is 18th on hectares and dead last on count. Across all 33 boroughs the two measures are negatively correlated — more total green space goes with fewer separate green spaces, fairly reliably.

That is not a glitch. It is two different kinds of city:

• Inner London has many small green spaces. Squares, churchyards, pocket parks, canal-side strips. Islington has more of them within a mile of the average postcode than anywhere else in London, and almost the least green space by area.
• Outer London has few large ones. Havering, Hillingdon and Croydon have substantial parkland in big contiguous blocks, with long stretches of housing in between.

Which of those is "greener" depends entirely on what you want from it. Five minutes to a square where you can sit with a coffee is a different amenity from twenty minutes to somewhere you can walk a dog for an hour, and no single number ranks them.

The measure has real limits

Worth being straight about what this data does and doesn't include. The green space figures come from Ordnance Survey's Open Greenspace dataset, which maps publicly accessible green space: parks, playing fields, commons, allotments, cemeteries, golf courses.

Which means:

• Private garden squares don't count, and there are a lot of them in Kensington, Bloomsbury and Notting Hill. Locked to residents with a key, so arguably correct to exclude — but it makes some very leafy streets look bare.
• Your own garden doesn't count. A street of terraces with gardens and a street of flats without them score identically.
• A golf course counts the same as a park, despite being considerably harder to have a picnic in.
• Quality is not measured at all. A well-kept common and a scrubby verge are both hectares.

We weight green space at 10% of the overall AreaScore for roughly these reasons — it matters, but it's the criterion where the public data is furthest from what people actually mean when they say they want to live somewhere green. Crime, transport and schools all get more weight because the data underneath them is closer to the question.

If green space is your priority

Decide first which kind you mean.

For space to properly disappear into — long walks, room to run, somewhere that doesn't feel like a city — the outer south-west and outer north-east are where the hectares are. Richmond, Merton, Redbridge and Ealing all combine substantial parkland with reasonable transport, which is rarer than it sounds, because the two normally trade against each other.

For green you'll actually use on a Tuesday — twenty minutes outside, a bench, somewhere to take a toddler — inner London is better supplied than its hectare count suggests. Islington, Southwark and Tower Hamlets sit near the bottom on area and near the top on the number of separate places to go.

The boroughs low on hectares are not short of green space by accident. They are dense, central and built up, and that density is precisely what buys them the transport, the amenities and the small squares. You are choosing which trade you'd rather make, not finding a borough that has escaped it.