I like most authentic British accents. It's just those phony ones that American actors put on in roles where they're not even portraying Brits that get to me.
I don't know what you call it, but there's a particular habit of a lot of Brits where they substitute the "v" sound for the "r" sound -- the word tray becomes tvay, the word relax become velax, et cetera. When I first heard this, I thought it was a speech impediment, as I've heard a few Americans with that speech impediment, but I've found that it's so common among Brits that it must be a phenomenon related to an accent, not an actual speech impediment.
I actually kind of like how it sounds, though.
