Lady Margaret Beaufort was the mother of Henry Tudor (later King Henry VII).
She was descended from King Edward III, therefore she and her son felt that he had a claim to the throne.
They had always maintained that the Edward IV--Elizabeth Woodville marriage was a sham, and that their children were illegitimate.
Therefore, when the ruling that came from London agreed with them, Margaret and Henry went into overdrive in their campaign to get the throne for Henry Tudor.
Part of this campaign was to smear the reputation of Richard III any way they could. It was a ruthless campaign.
When Richard's wife, Anne, died, they spread the rumor he had poisoned her.
Lady Margaret Beaufort had had rooms for years at the Palace in London and had means, motive and opportunity to arrange for the disappearance of the boys.
Lady Margaret Beaufort and Henry Tudor had been quietly plotting to overthrow Richard III, and gathering an army. The head of one of these army factions, waiting in the wings for their time, was the powerful husband of Margaret Beaufort, Thomas Stanley.
Margaret knew that if her son could gather support and oust Richard III, there would soon be an uprising to install one of the young Princes as King instead of her son. She had to get rid of the princes before her son attacked and ousted Richard, whether Richard lived or died as a result.
The two Princes in the Tower had a much more clear right (if Richard was gone) to the throne if Parliament could be convinced of their legitimacy by their supporters......namely Margaret of Burgundy (their aunt) and Emperor Maximillian.
in August 1485, Henry Tudor and his uncle, Jasper Tudor, landed in Wales with a contingent of French troops, and marched through Pembrokeshire, recruiting soldiers. Henry's forces defeated Richard's army near the Leicestershire town of Market Bosworth. Richard was slain, making him the last English king to die in battle, and the last Plantagenet king of England.
Henry Tudor then ascended the throne as Henry VII.
The plot had been hatched by Margaret Beaufort's husband, Thomas Stanley.
He had played both sides of this game, pretending and promising to be loyal to Richard, but at the last minute, he and his men were for Henry Tudor at the Battle of Bosworth.
This turned the tide.
To blame Richard III for the disappearance of the young Princes served Margaret and Henry Tudor's cause very well. It painted Richard, the dead king, as evil, so his supporters would be dissuaded. It left Henry Tudor, the true murderer, blameless as he began his reign.
How convenient for them that the whole family was now dead.
The program and Philippa Langley's theories are extremely interesting and they have provided food for thought.
However, I still point the finger at Margaret and Henry Tudor, IF the boys were in fact murdered.