Small world ia a scam! When I was on vacation in London my father and I heard the “fact” on the tourist bus that you couldn’t be on Picadilly Circus more than 43 minutes or so before meeting someone you know. We sat there for over an hour and didn’t see anyone.
But then again, we were at an airfield for a pilot meeting earlier during that vacation. And it turned out that the guy who owned that airfield was stationed in Germany at the same town and at the same time my father lived there as a child.