You're absolutely mad - this has no relation to reality at all.
> Is it fish caught in that same day like you can get in any Greek taverna in the Cyclades?
The UK has some of the richest fishing waters in the world. We have so much that we export worldwide. Of course it's available in London.
> Suburbia? Is there anything else for a radius of 50-60 km?
How big do you think the suburbs of London are? It's not LA. Draw a 60 km radius circle around London and take a look at the expanse of rural England for yourself.
Northeast of London you have East Anglia which two of its counties are really only known for their agriculture. Suffolk [1] & Norfolk [2]. Southeast you have the flower garden of Kent [3]. I live Southwest next to a train line called the Watercress Line [4] that was named such as it ferried fresh watercress into London.
> Is it fish caught in that same day like you can get in any Greek taverna in the Cyclades?
Yes
>Or frozen fish brought in from half a continent away?
You can get that too.
The negative response you are getting from users is because you are completely wrong about inability to get high quality, same day picked/slaughtered/fished food in London.
edit: in regard to frozen fish, I trust that the Japanese (who regularly freeze the absolutely highest grade Tuna during transit) know what they are doing.
