"Native English speaking writer" or...,
"American writer" or...
"Writer educated in American University with degree in English".
And I was kind of wondering... is there really that much of a difference in terms of writing skills between, say, a U.S. born writer and a really talented writer who was not born in the United States or U.K. (and has never lived in either of these countries)?
That is, let's say someone looked at a random article, e-book or even sales copy... can they accurately guess whether the content was written by a U.S./UK writer or a writer from another country?
P.S.: This kind of reminds me of some of the martial arts schools I see, where they would advertise something like, "...Learn from a true oriental master...".