pat, the thing about people who inherited the throne very young was that they were mostly bad rulers who came to a bad end. Ethelred the Unready, aged under ten, was definitely unready (I know that's not what the name really means). Henry 6, Richard 2, Edward 6. On the other hand the oldies weren't great either: Edward 7, William 4, George 4 - they'd all wasted decades doing nothing.