The innermost City of London sees a fifty-five-fold population increase during the day. So how big is "London"—really?by Alasdair Rae / November 3, 2017 / Leave a comment
Where are the actual boundaries of London? If someone were to ask you “what’s the population of London?,” you might be tempted to say “8.8 million,” because that’s how many people lived there in 2016 according to the Office for National Statistics. If you’re a wonk with any sense of self-respect, however, you would be compelled to ask “what do you mean by London?” Or, if you’re an uber-wonk, you might go further, and ask: “what do you mean by ‘population’?” Add these two questions together and you arrive at a perennial problem for urbanists and planners worldwide: the issue of how we define cities, and where their boundaries lie. This seemingly arcane question has real-world implications, because big cities like London need to understand their “functional economic geography” if they are to plan properly; for infrastructure, transport, housing, economic development and so on. Thus, the question of where London “ends” may seem odd, but it’s important. One way to think about where cities end is to look at their commuter footprint. Within the UK London has by far the largest. This is something I attempted to map using data from the most recent Census to visualise the pull of London’s labour market. As far out as Cambridge, Hastings, Margate and Salisbury, one in twenty workers commute to London. This is not surprising, and it would be a stretch to claim ‘London’ extends this far, since the area in the map has a population of around 15 million. But London does draw in workers from far and wide to the extent that the population swells to more than 10 million each workday. The innermost City of London, home to around 10,000 residents, sees a fifty-five-fold population increase during the day, with more than half a million workers making a living there. This makes it, for a significant part of the week, one of the most densely populated places on earth, with over 190,000 people per square kilometre. If the wider London commuter-shed is too big to be considered the point at which London ends, how else can we draw the line? One useful way to think about it is by using the concept of the “travel to work area” (TTWA), developed by Professor Mike Coombes at Newcastle University. The method is complex but the idea is simple. We define these using commuting data, so that 75 per cent of people who work in a TTWA also live there. We can think of TTWAs as self-contained labour market areas, and there are two covering the London area—one for London itself (8.4 million people) and a separate one for Slough and Heathrow (1.6 million people). This gives us a better idea about where London might end, and a combined population of just over 10 million. But of course, even TTWAs aren’t definitive, and they aren’t directly comparable with definitions of other world city boundaries. One recent useful approach of note in this respect is the European Commission’s “Global Human Settlement Layer,” which maps towns and cities across the world using a consistent methodology. On this measure, the population of London is 9.7 million and it ends somewhere beyond the M25, but not by much. By comparison, the same dataset puts the population of the Tokyo urban area at 33.7million, New York at 15.2 million and Paris at 10.2 million. This new approach has won many admirers, but ultimately the question of where exactly London ends is a subjective one, and we’re likely to get a different answer depending upon who we ask. That’s why I decided to crowdsource an answer to this vexed question, using a ‘draw your city’ web mapping tool. Building on the work of others, I put it together in an afternoon and let anyone draw their version of London, and any other city they wanted. The results were fascinating, and in a short space of time I could download 183 slightly different versions of ‘London— along with some interesting comments. Just for fun, I patched these together in a short animation, to emphasise the fact that the question of where London ends has multiple answers, but many similar ones. As you can see, the vast majority of people drew shapes within the limits of the M25, perhaps hinting at a view that London ends there. Well, not so fast perhaps, since this was only a short-lived experiment on a subject that has been the subject of debate for decades. The current administrative division into 33 local authority areas as ‘Greater London’ serves many purposes and has been with us since 1965. Its population is at an all-time high and will soon officially exceed 9 million residents. As we know, though, the population of London already peaks at over 10 million during the day and its pull as a magnet for commuters extends well beyond the official boundaries. The question of ‘where London ends’ is then perhaps best answered by looking at how far people are willing to travel for work and leisure. For some, it might be as far as what a marketing firm rather craftily dubbed ‘North Londonshire’ (aka North Northamptonshire). For others it might extend only as far as the limits of Zone 1. But, from a functional point of view, it’s clear that London extends beyond the boundaries of its administrative area and its wider economic footprint makes a significant imprint on the South East. The real question might therefore be: ‘is London too small?’ Where does London end? Add your own at http://ajrae.staff.shef.ac.uk/nhood/ Find out more about Alasdair Rae’s work on his website.