Interesting discussion. As someone who has no accent at all (by American standards) since I'm from the middle part of the country where they send newscasters to learn to speak neutrally, I think it's funny to see people in the U.K. discussing other people in the U.K. intentionally picking up other U.K. accents. I'd never know the difference, myself. I am getting pretty good at telling what county Irish people are from by listening to them talk. I find the whole thing fascinating, the assumptions people make (presumably) about others based on features (such as accent) that are indistinguishable to much of the rest of the world.

As far as singing, I think that I'm more of a mimic when I'm first learning a song, and therefore sing it like the person I learned it from until I've sung it many, many times on my own (in the shower of course). Working in an "Irish" pub with entertainment every night, I would get so used to singing along with one singer's version of a song that when a new act came along, it was like a different song, even if the two groups had both played there a thousand times. By now I've heard so many of the people who do Irish around here that I'm all mixed up (although to be fair "mixed up" can fairly accurately describe my natural state as well).