The answer to your question is Svejk...whoever the British people vote for !
Actually, if we did have a vote and Betty put her name forward, I would willingly vote for her. She has more political experience than almost anybody alive in Britain today. She has seen Kings, Queens, Prime Ministers, and Popes come ago since 1952. She seems to have a sensible head on her shoulders, although I can't say the same for most of her relatives.
But we would have choice in a Republic, which we don't have now. Its like dave, or even Blair saying...well, I'm going to stay in Number Ten until I die and then some relative of mine can take over until he or she dies. Nobody would accept that but some seem to have no problem with accepting the same sort of thing with our Head of State. Not logical or rational of course, but any change won't happen in my lifetime.