Casting limits/UK only?????

[susanbones2003]

I just read a post where someone thought it was a rumor that only UK 
actors would be cast in HP movies. I don't know all the scoop on 
things but it has always been my impression that this was true, that 
only UK actors could be cast in HP roles, this being JKR's desire. 
Could someone more knowledgeable than me straighten this out? You 
know that way in which you know something but couldn't put your 
finger on the proof if your life depended on it? That's what's 
happening to me. And if this is wrong, does someone have a source?
Jennifer