Okay everyone, who’s up for an invigorating game of “pin the green belt on the net change in housing supply map”?

The map above shows the change in the number of homes in every council in the south east of England between 2001 (when we didn’t have a housing crisis) and 2016 (when we emphatically did). It’s the work of Neal Hudson, an independent housing analyst, who got the data from this government dataset (table 125, if you’re interested).

Perhaps the biggest trend that jumps out on you is that there’s a ring of councils around London that have, let’s say, not done a great job of increasing their housing stock.

Further from London, the colours get darker as the numbers go up. A lot of inner London boroughs have done better, too: Tower Hamlets has managed more than 24 per cent; Islington, Hackney, Newham, Westminster and Southwark have all done over 18 per cent. (That tiny sliver of beige in west London, incidentally, is Kensington & Chelsea, the site of the Grenfell fire, which has barely built anything.)

Between those two, though, there are several dozen light yellow or beige boroughs, in outer London or in the commuter belt beyond it, representing only small increases in housing numbers.

Now what does that pattern remind me of?

The Green Belt. Image: Lower Thames Crossing Association.

Communities secretary Sajid Javid is soon expected to reveal plans which will force councils to increase their house building targets. That ring, Hudson argued, is very likely to be in his sights:

Is this enough new homes? Between 2001 and 2016, the UK’s population increased by around 12 per cent: at first glance, it looks like at least half of the councils on this map grew their housing stock by more than that (the three darker shades), so maybe things aren’t too bad.

And yet, that 12 per cent probably understates the population growth at this end of the country: as we’ve noted before, England’s fastest growing cities are all in the economically prosperous south.

What’s more, with a few exceptions in inner London, it tends to be the councils further from London that have done most to increase their housing stock. That’s a problem, for two reasons. One is that these councils had smaller populations to start with. A 20 per cent increase on a small number may be a lot less homes than an 8 per cent increase on a big one.

The other is that many of these new residents are likely to work in the capital, meaning long commutes, big carbon footprints and so on. The green belt is protecting the inner ring of commuter towns from sprawl, while loading it all onto places further out.

Oh yes – and consider that housing costs in the south have ballooned, of course. That suggests we’re not building enough homes, too.

Jonn Elledge is the editor of CityMetric. He is on Twitter as @jonnelledge and also has a Facebook page now for some reason. 

Want more of this stuff? Follow CityMetric on Twitter or Facebook.