"The union of York and Lancaster entailed the demonization of Richard III."
Richard III c.1520 (after an original)
Public DomainRichard III c.1520 (after an original) - Credit: Wikimedia Commons

After Richard III's defeat at the Battle of Bosworth Field, it proved necessary to 'forget' the Plantagent line, of which Richard III was the last.  For the new Tudor dynasty to rule with strength Henry VII had to 'demonize' Richard III.  Richard's notorious involvement in the death of the Princes in the Tower has since been questioned, as the truth of what happened to them, and by whom, is not known.  But the story, and belief in Richard's involvement, were popularly held and was capitalised upon.  Much modern popular belief in the old myth relies upon Shakespeare's play Richard III, with Richard being played both as a villian and as someone older than he actually was.  Only 32 when he died in 1485, he has invariably been played by actors considerably older.  For instance, Laurence Olivier was 47 in his 1955 film and Sir Ian McKellan was 56 in his 1995 version.