Princes in the Tower "the murther of his nephews towards the world", indicating that the boys did indeed meet their end during Richard's days. It is also unlikely that the princes would have been kept alive in secret by Richard for 2 years after their last sighting while rumours of his responsibility for their murder circulated. Some writers have also accused John Howard, 1st Duke of Norfolk; Margaret Beaufort, Henry VII's mother; and Jane Shore (Edward IV's mistress). Pollard writes of these theories: "None deserve serious consideration. The problem with all these accusations is that they beg the question of access to the Tower
Princes in the Tower his brother from the Tower before it was too late", but that, when the Duke of Buckingham became involved, it shifted to support of Henry Tudor because "Buckingham almost certainly knew that the princes in the Tower were dead." Alison Weir proposes 3 September 1483 as a potential date; however, Weir's work has been criticised for "arriving at a conclusion that depends more on her own imagination than on the uncertain evidence she has so misleadingly presented." Sir Clements Markham suggests the princes may have been alive as late as July 1484, pointing to the regulations issued by Richard III's