Last week we published a selection of graphics showing how London's population had grown, how it had changed relative to the country that contains it, and how, on some definitions, the city was threatening to break its bounds and swallow large chunks of the south east. Then we published a bunch of maps to track the rise of the suburbs.

What we didn't do, though, was consider how the 8.6m Londoners were distributed within the city itself. Look at that and you'll swiftly learn that, in one crucial way, the British capital is very, very weird.

To metroland!

London's population was initially crowded into what is now inner London*: that's no surprise, as that’s where the city began, and as recently 100 years ago, much of what is now classified as "outer London" was open countryside dotted with villages and small towns.

From the late 19th century onwards, though, the population of what is now outer London began to grow, and grow, and grow. It overtook the population of inner London some time in the 1940s; the latter has never seriously threatened its demographic dominance since.

We've written before about the post-war depopulation of London. Split the city into its inner and outer rings, though, and it soon becomes clear that this description is, well, a bit simplistic.

Source: Census data.

The population of inner London actually peaked a quarter of a century before 1939, hitting 5m around the time of World War One. But it then starts to slide – at first slowly, but then accelerating after about 1930. From peak to trough, in the early 1980s, it falls to more than half.

But that’s just inner London. The population of outer London actually keeps rising until the 1950s, before flattening out. It dips a little after that, but never by more than about 7 per cent. Outer London is relatively stable.

In other words, the post-war depopulation of London was actually the depopulation of the inner city. In the “Metroland” years of the 1920s and 1930s, people moved out to more spacious newly homes on the shiny new tube lines. Later, this became an act of deliberate government policy, to clear bomb-damaged slums and decant a fair chunk of Londoners to new towns in the commuter belt.

This map, from Quod's Barney Stringer, tracks this trend, in two different ways. The size of the boroughs represents their population in 1939. Their colour represents their change in population since.

Image: Barney Stringer/Quod.

At a glance you can see that, on the eve of WW2, the inner city was still relatively crowded, but has massively depopulated since. Most of the outer boroughs, by contrast, have grown in population; and the more suburban the borough, the more it's likely to have grown.

Today, while both parts of the city are growing once again, around 60 per cent of Londoners live in the city's outer boroughs...

Source: 2011 census data.

...and, while we hear much less about them than some of the inner ones, all six of London's largest boroughs by population are actually out in the suburbs:

Source: 2011 census data.

What makes London weird

Okay, we promised you that London was weird, and you've patiently read this far in the hope of finding out why. So, here it is.

These awesome graphics come from the clever people at the LSE Cities programme. They show the average population of each part of a city over a 24 hour period (including residents, workers, tourists, etc). The higher the peak, the more densely populated the city. You can click for a larger version.

Click to expand. Images: LSE Cities.

You can no doubt see the pattern already, but let's hammer it home. Here are some similar graphics, also from LSE Cities, but this time only including residential population. (We’ve manipulated them a little to make them display better on our site, but we’ve not amended the graphics themselves.)

Click to expand. Images: LSE Cities.

...and here's London.

Click to expand. Images: LSE Cities.

Look at all that empty sky.

Two things stand out from this.

1) Whatever way you count it, London is much, much less densely populated that most megacities. We sadly don't have a similar graphic for Paris, which one might think a better comparator for London than, say, Delhi; but suffice it to say that the average density in Paris proper (the equivalent of inner London) stands at 21,500 per km2, which is higher than the peak population density for London listed in the graphic above.

2) London's population is much more evenly distributed. Most cities have a centre that's full to bursting, but then trail out to less populated suburbs and a relatively empty hinterland. In London, though, the inner city is not that much more dense than the suburbs, or the ring of commuter towns that surround it.

Here's a clearer image:

Click to expand. Image: Skate Tier/Wikimedia Commons.

London, in other words, is a freak.

The good news here is that, when you look at it like this, the city has loads of room for all those extra people wanting to come here. We could fit nearly 2m more people into the inner city, without any part of it exceeding its previous peak population. Four boroughs are, in one sense, half empty:

Click to expand. Image: Neil Hudson/Savills.

Maybe everything's going to be alright.

For the purposes of this article we’re using the Office for National Statistics definition of inner London, which includes Haringey and Newham, but excludes Greenwich. This is the third part of a series about how London's population has changed over the last 75 years. You can find the previous parts here and here.