Percent of workers in a locality that commute to Greater London (source: Alasdair Rea)
Percent of workers in a locality that commute to Greater London (source: Alasdair Rea)

I’ve written a number of times before about the difficulty of defining how big or extensive a metropolitan area is i.e. where it “ends”. The standard approach – administrative boundaries – is patently inadequate to capture the urban processes happening on the ground, although it’s still routinely relied on by the media to underpin stories about excessive sprawl (see Does Melbourne really extend five times further than London? and How big is Melbourne?).

My view is the search for a workable definition begins with the extent of contiguous or near-contiguous urban development but ultimately ends with the geography of economic and social “connection” between one place and others.

The key connection is commuting because it’s a frequent and regular connection between places and because it’s of immense importance both to workers and to the origin and destination localities. It helps that there’s usually data available too.

The first exhibit, developed by Alasdair Rae from the University of Sheffield, maps the proportion of workers living in various localities across England and Wales who commute to Greater London i.e. to jobs in the dark “bulls-eye” (1,569 sq km).

Obviously workers who can afford to live in Greater London also tend to work in Greater London; but it’s clear the city has a huge economic influence across a very large part of the UK.

If some of the percentages in the exhibit seem small, note that only circa 6% of workers living in the outer suburban Melbourne municipalities of Casey and Cardinia work in the inner city i.e. roughly within a 5 km radius of the CBD. In the case of Mornington Peninsula it’s only around 3%. Of course even fewer work in Melbourne’s CBD.

The first exhibit suggests it’s insufficient to define the extent of a city like Greater London solely on the basis of a usually longstanding administrative boundary.

The area covered by London+, showing Greater London and the famous greenbelt
The area covered by London+, showing Greater London and the famous greenbelt

The second exhibit is a map of a more expansive “London” developed by Dr Rae. It’s based on localities that can access Greater London within a 90 minute maximum commute. Dr Rae calls the area London+.

My idea was not to try to say any of the London+ areas are in or part of London but rather that they play an important role in the vast, complex London labour and housing markets – some areas more so than others, obviously. I wanted to identify areas that, owing to their physical and temporal proximity could be considered part of a much wider commuting and housing zone.

What’s very important here is that London+ has a population of 18.9 million. As Dr Rae notes that’s more than a third of the population of England.

But what’s even more interesting is the population of Greater London is 8.5 million, meaning more residents of London+ live outside of Greater London than within it.

The size of a city isn’t defined by some administrative boundary or by the extent of contiguous urban development; Greater London’s famous greenbelt doesn’t prevent high proportions of workers living in surrounding areas from commuting to the city.

London isn’t unique. The extent of Australia’s cities is much larger than is commonly assumed. Wisely, the ABS recently adopted the concept of Greater Capital City Statistical Areas, which seek to capture the labour shed of each city.