I was always sure he was Australian, but I just saw that commercial where he is asked if he is British or Australian and he says "actually I'm from...(commercial cuts off)" any guesses/proof are welcome
also if he is from Australia/Britain is he an American citizen? or does he have a work visa.
The guy who does his voice is British, but Geckos aren't naturally found in England, so he would probably be from Australia, but educated in the UK in that case.