I'm British and I definitely do not, or know anyone who does, talk like that.... The royal family are probably the only people to speak posh or well spoken, other than that it's all slang talk. Visit England and you will see the spoken english is poor, I type better english than I talk lol
As neither an American nor a British, I would honestly say the American accent is more understandable for me, but the British is definitely classier, not sure how to explain this, I've been to London not too long ago and I was very happy hearing the British accent, although I looked very idiotic trying to comprehend what people were telling me, it's mainly due to too many American movies and TV shows, lol.