Smithfield market is a really interesting place, and if you can believe it smack dab in the middle of the market is a fantastic cocktail bar – Oriole[1]. Unfortunately they're closed now due to the coronavirus, but once they reopen I highly recommend a visit.
I am not affiliated with Oriole or Nightjar in any way, just a huge fan. (So much a fan that I've flown in to the UK on several occasions just to go to these places, can't praise them enough!)
I've just google image searched for the Spitalfields Market, apparently people in here believe that plums and avocado grow just outside of London (because that's what I saw in those photos).
What I'm saying is that London cannot compete with countries/provinces where plums or what have you grow just a 15-min van drive away from said restaurants, and as such calling a city like London "the food capital of Europe" is a joke. Anyway, also calling Napoli the "food capital of Europe is a joke" because of its size and population density, I can assure you that a 2- or 3-hour drive to the South can get you to some random Calabria small town with way better food than you can get in most of Napoli.
But the food-mania is high with many people who think that just because a place happens to have money it also has good food.
Plums grow in England. I don't know where you got the idea that they aren't possible to be local produce or the idea that you cannot run a good restaurant more than 15 minutes drive from a plum tree. I think the food mania is in the room but it's not coming from me.
> I've just google image searched for the Spitalfields Market, apparently people in here believe that plums and avocado grow just outside of London (because that's what I saw in those photos).
London is only 35 miles away from the sea, how far do you think it is to a field.
As to your Van Drive: For example, Brixham (160 miles) is a popular place to get high quality seafood for the posher end of the restauraunts, this is ~3hr30. Getting fresh ingredients to london is a completely solved problem.
I was really confused by this comment because Spitalfields market as far as I know isn't really a food market, or at least isn't these days; but what they're probably referring to is New Spitalfields Market, i.e. not the one in the City. I wonder why they chose the same name as the old market, super confusing.
https://en.wikipedia.org/wiki/New_Spitalfields_Market https://en.wikipedia.org/wiki/Billingsgate_Fish_Market https://en.wikipedia.org/wiki/Smithfield%2C_London#Market
You have to arrive at these markets extremely early in the morning. This is the case with any b2b market, e.g. Tsukiji Fish Market in Tokyo:
https://en.wikipedia.org/wiki/Tsukiji_fish_market