However, with his full name being Charles Philip Arthur George, there are a number of other names he could select, if he so wished. […] [S]peculation has grown that he could choose his third middle name, George, to reign as King George VII. Not only would this be him giving his own middle name precedence, it would also serve as a nod to his grandfather, King George VI, who was Queen Elizabeth II’s beloved father.
Of course he could also choose to rule as King Philip I or King Arthur I.
King Arthur I would be an absolutely hilarious choice.
I would absolutely insist on King Arthur II if I went with Arthur.