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the legitimacy of his wife or her claim as heiress of Edward IV called into question, prior to the marriage he had repealed the "Titulus Regius" which had previously declared the princes (and Elizabeth) illegitimate.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 of Scotland. After a failed attempt to invade England he was captured. He retracted his claims, was imprisoned and later executed. Many modern historians believe he was an imposter, whose supporters accepted his claim for political reasons. The fact that two persons claimed to be Richard led the 18th century writer Horace Walpole to argue that Richard had in fact escaped death, and that Warbeck genuinely was Richard, a view also supported by Malcolm Laing. Walpole, however, later retracted his views and stated that he now believed the princes to have been murdered by Richard III to secure his hold