By June 1553, Edward VI was seriously ill. The succession of his Catholic half-sister Mary would compromise the English Reformation. Edward opposed Mary's succession, not only on religious grounds but also on those of legitimacy and male inheritance, which also applied to Elizabeth. He drafted a document in which he undertook to change the succession, as had his father. Edward passed over the claims of his half-sisters and settled the Crown on his cousin Jane Grey. In doing so he also passed over Frances who otherwise would have been the heir presumptive. It is not clear to what extent Northumberland may have influenced the king's plan, but he supported it.