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.