On a world-wide version, it would have trouble with me.
Even though I've lived all my life in Sydney's southern suburbs, I've had many people over the years wonder where my accent is from. But I'm Australian!
What I think has happened is that the same things that originally engendered the early versions of the English 'Received Pronunciation' at the likes of Oxford happened to me: namely, the influence of reading a lot. As a child, I was a voracious reader. When I moved out of home a few years ago, even my mother did not fail to be surprised at just how many books I own. And I've read almost all of them.
This was borne out a few years ago when I heard a black American preacher who had spent a lot of time in university. His accent was very unusual: to a lot of people it sounded a little British, but not quite, yet we knew he was from the US and could here a lot of New York in there, too. It took a friend of mine who is even more accent-aware than I am to point out that it's because he has so much education. It was an educated accent.
Wade.
"Don't give up!"