Interesting. I live in central London and moved flat a few years ago.

Only noise issues i had were motorcycles with modified exhausts and emergency sirens. It's really quite confusing why they are considered necessary. New flat is high up and has 3 inch thick windows so we can't hear a thing unless its really nearby. But i have the door open sometimes and you can hear what sounds like a massive terrorist response of emergency sirens. THe you look over and see its one ambulance traversing traffic in an area with many angled buildings.

I recall years ago there was a plan to move them to white noise based systems. What happened with that