Princes in the Tower becoming king, Henry married the princes' eldest sister, Elizabeth of York, to reinforce his claim to the throne. Not wanting the legitimacy of his wife or her claim as heiress of Edward IV called into question, prior to the marriage he had repealed the "Titulus Regius" which had previously declared the princes (and Elizabeth) illegitimate. Markham suggests the princes were executed under Henry's orders between 16 June and 16 July 1486, claiming that it was only after this date that orders went out to circulate the story that Richard had killed the princes, and that the princes' mother, Elizabeth Woodville,
Princes in the Tower to speculate when or by whose hand." During the reign of Henry VII, two individuals claimed to be Richard, Duke of York, who had somehow escaped death. Lambert Simnel initially claimed to be Richard, before changing his story and claiming to be Edward Plantagenet, 17th Earl of Warwick. Perkin Warbeck later claimed to be Richard, appearing in Ireland and calling himself king Richard IV. Margaret of York, Duchess of Burgundy, formally recognised Warbeck as Richard. Margaret, Richard III's sister, an unrelenting opponent of Henry VII, had previously recognised Simnel as Warwick. Warbeck was also accepted as Richard by James IV