If John Potter was born in any locality within the realm of George II or III, then he was not a foreigner as he was a natural born subject of the British Kings, so did not need to become naturalised. The colour of his skin did not determine his nationality. Among those men and women transported to the British Colony of New South Wales were people with surnames including GREEN, White, Black, Brown, Potter, Archer, Bowman, Caesar, BLUE .... Billy Blue and Black Caesar ... two very famous men of colour in NSW history. I am sure though that John Green's skin colour is not indicated in his surname, just as I am sure his ancestors include people born St Kitts in the 1770s and through into the 1810s.
JM.