If they had stopped her marrying Philip or for some other reason HRH had decided she wouldn't be Queen what would have happened? Presumably we would have got Margaret. Would she have been as headstrong as she was? I imagine she would have brought the monarchy to its knees. We might not have a monarch now.
That's an interesting thought. Apparently, when King Edward V111 abdicated, some in parliament thought that Bertie was unsuitable king material and proposed that Queen Mary would reign as Queen Regent. If that had happened, the Duke of Kent would now be king.