The noisy American tourist used to be a staple of British comedy in the 50s and 60s. Garlanded with cameras worn over noisy Hawaiian shirts, he was generally called Hank or Elmer and smoked a cigar. But the thing that got the British goat, and supplied the tension that led to the comedy, was that he talked so loud you couldn't avoid hearing him. The thing everyone agreed on was that Americans were all mouth. This was taken to be the expression of their new-found economic virility.
Last night I took a number of trains into the West End, which is doubly busy in the pre-Christmas period. On one train were four American university students, presumably over here as part of their course. They talked quietly and their demeanor was, if anything, faintly apologetic. It struck me that I hadn't heard a noisy American in London in ages. You can attribute that to the reduced amount of tourism from that part of the world and the fact that the last ten years have made Americans acutely aware that their nationality can make them a target, but it's certainly happened.
On the other hand, while the visiting Americans have got quieter and more polite an increasing number of Brits seem incapable of recognising that not everyone who's sharing the public space with them wants to hear everything they have to say and consequently talk louder and, though they probably don't realise it, more aggressively than ever. And in most cases they have pitifully little to shout about.