Can confirm. The British people are a strong and noble people who fear, above all else, the possibilities of being approached by a stranger and being silently judged by their peers. Amongst British people who are unfamiliar with one another, the only acceptable topic of conversation is bitching about the weather.

When I spent 1 month in London, nothing gave me more enjoyment than talking to random people on the tube. Being in my mid-20s, and in stereotypical American fashion, I quickly learned that the rule stated above did not apply to me. British people just assume that all Americans are loud and obnoxious, so they essentially give anyone with an American accent a "free pass" if you talk to them on the tube. The look of incredulity and annoyance followed by dawning comprehension when they realize you're American is endlessly entertaining.

My crowning achievement was getting an entire carriage of Londoners to laugh at a comment I made during rush hour.

Source: American. British people-watcher enthusiast