Great piece, and thanks for all the juicy tips. Just one thing: London, for me, is much more aggressive than Paris. The proxemics are indeed different – as is true in all "south" cultures, Parisians are more comfortable in tighter, denser spaces, more in-your-face, more likely to start shouting at you for doing something silly, BUT I never see any escalation to violence, which, I swear, I see at least once on every trip to London. No one throws a punch. I've never seen a headbutt.