Today's post is about catchment areas, or more specifically catchment populations, i.e. how many people need to live in a neighbourhood before it's worth opening a business there. You need a lot of people before it's worth opening a piano shop, rather fewer before you open a hardware store and fewer still before you open a small supermarket. But is it possible to estimate roughly how many?
It was corner shops which set me off thinking. Step off the main roads in the London borough of Newham and you enter a grid of Victorian terraces where numerous corner shops still exist. There are nowhere near as many as there would have been, most have been transformed into homes or flats, but isolated street corners still have convenience stores for the convenience of very local residents. Racks of fruit and vegetables, shelves of kitchen roll and cleaning products, stacks of tins, supplies of rice and sauces, a display of sweets, maybe beers, probably a stash of cigarettes behind the counter and would you like a lottery ticket with that? Variety may be limited and you can expect to pay a premium, but proper corner shops still keep micro-neighbourhoods ticking over.
But how many people need to live nearby to ensure a corner shop is economic?
It's usually too hard to work this number out. People don't always go to their nearest corner shop, catchment areas overlap and the influence of larger supermarkets distorts things somewhat. It's generally easier to determine catchment populations in the countryside, where single shops support a village, than it is in heavily-built up areas. But I think I've found a bit of Newham that allows me to give a calculation a shot.
This is HP Food and Wine, the sole corner shop/grocery store serving a thin splinter of streets in East Ham. It's also a really well defined splinter because one side is blocked by the Northern Outfall Sewer, the other by the A13 dual carriageway and the far end by a school. Residents of Roman Road, Saxon Road and Stokes Road can't easily walk anywhere else, and potential shoppers from elsewhere are never going to walk in. I can therefore define an accurate catchment area and count the number of homes, which is about 550, and translate that into an estimated local population of 1500. This seems appropriately ballpark.
My Dad's Norfolk village has a population of about 1300 and has a village shop, so that's some reinforcement. My brother's Norfolk village has a population of about 800 but no longer has a village shop, it closed a few years ago, suggesting 800 is too few. The village where I used to live in Suffolk also has a population of about 1300 but only has a shop because the community organises it, not because it's economic. And Croxley Green where I grew up has a population of about 12500 and I think supports seven grocery stores, so that's more like 1800 people per shop. I'm going to suggest that 1500 is a reasonable stab at the catchment population for a corner shop.
I've long wondered what the catchment population is for a coffee shop. Small outlets seem to thrive on fairly minor footfall, and even quiet museums seem to think it worthwhile to have a corner serving drinks. But this is a much more difficult thing to count or tally because where do you draw the line, and what's the difference between a cafe and a coffee shop anyway? I'll have a go because in 2017 I compiled a definitive list of all the coffee-serving shops in the E3 postcode and I also know 52,000 people live here. So that means back in normal times E3 had ten what-I'd-call-proper coffee shops, that's one per 5000 residents, and 33-ish coffee-serving outlets, that's one per 1500.
I can do better with pharmacies because they're more easily countable. The E3 postcode has 11 pharmacies, that's one per 4800 residents. Croxley Green has 2 pharmacies, that's one per 6250 residents. The Isle of Wight has 27 pharmacies, that's one per 5200 residents. And if you scale up to the UK as a whole it has 14000 pharmacies, that's one per 4850 residents. These are impressively similar ratios suggesting there's a nationally prescribed population per dispensing chemist. I don't think there actually is, I think it's all just market forces, but you probably share your local pharmacy with about 5000 other people.
And let's do schools, specifically primary schools because they tend to be located close to home. The E3 postcode has 12 primary schools, that's one per 4300 residents. Croxley Green has 3 primary schools, that's one per 4100 residents. The Isle of Wight has 41 primary schools, that's one per 3500 residents. And the UK as a whole has 21000 primary schools, that's one per 3300 residents. Primary schools vary a lot in size so are hard to properly compare, but overall you need a slightly smaller population for a primary school than you do for a pharmacy.
And pubs, pubs are interesting. The E3 postcode has 15 pubs, that's one per 3500 residents. Croxley Green has 6 pubs, that's one per 2000 residents. The Isle of Wight has about 120 pubs, that's one per 1200 residents. And the UK as a whole had 47000 pubs pre-pandemic, that's one per 1500 residents. My local area is an outlier here, I suspect because a large proportion of the population don't drink alcohol, but overall it looks like 1500 has come up trumps again.
These are appallingly rough numbers that probably won't apply precisely where you live for a variety of geographical and economic reasons. But as catchment populations go a pharmacy needs about 5000 local people, a primary school needs 3500 and a corner shop, a coffee shop and a pub need 1500 each. I'll leave hardware stores and piano shops as an exercise for the reader.
