P.J. Harvey's "Let England Shake"

I've liked every song I've ever heard from P.J.Harvey but there's still one little annoying thing about her voice which continues to irritate me at the back of my mind even as I enjoy the songs. Why does she put an American sound onto her voice? I mean, there was a time, back in the beginnings of British rock, when singers thought they needed to sound American to be rock and roll. Then the Beatles, Rolling Stones and all the others broke through that perceived barrier. So why does a great singer these days still choose to put on an American vocal tone? I come from a Canadian father and an Irish mother but I grew up English so I'm interested in the importance people attribute to different kinds of voice. When I was in primary school the teachers made me stop imitating my dad's way of speaking because they thought it was "Americanism". In those days some British people couldn't tell the difference between Canadian and American. I'd love to hear P.J. Harvey sing with her own voice. But, that said, she does make a great sound in any case. I'm following her recent videos as they appear on her youtube page "Let England Shake". Here are two of the videos posted there so far: