Some of these girl signers mentioned here are not really in the same ball park as this Marina girl, she is a bit too weird, probably just for the sake of it over actual content. We've had weird female vocalists in the past, Polly Styrene, from X-Ray Specs, the Bowowow singer Annabella Lwin ect Or is it us lot getting old and this bird is cool to her generation? I still think she's rubbish. What about those Gypsys? No one's mentioned them, at least they had some energy.
Dave, I can't see how its ok to sing in a false American accent is acceptable and singing in a UK regional accent isn't but you being the constant pedant, I can't say I'm surprised.
I think it sounds good having regional accents. Look at the punk scene, I can't imagine Dead Citys by The Exploited would sound very convincing if Wattie Buchan sang it in the style of Bobby Darin.