@wowfudge
Regnal names are usually chosen so as to have positive associations or at least no negative ones. I think it is thought that Prince Charles is not likely to be King Charles because of his predecessors of that name.
It's funny though, because as soon as he was born, the Queen knew that he would be her heir and would remain so, barring something unfortunate happening. She must have known that the name Charles had connotations.