POD is Prince Arthur survives his initital fever at Ludlow and lives long enough to impregnate Catherine before dying a few months after OTL. Catherine delievers a healthy daughter, Princess Elizabeth Isabella, who is still alive when Henry VII dies in 1509. In this case, barring an Act of Succession by Henry, who is the immediate heir, Henry Duke of York or Princess Elizabeth? My understanding is that agnatic succession would prevail and Henry would assume the throne, but is this correct? And if Princess Elizabeth becomes Queen, how would Henry act as Regent and Heir Apparent? Richard III redux? I do not know enough to guess about the outcome, so I turn this over to those who do. Gentlemen, let the butterflies be free!