York's favourite medieval monarch, King Richard III, WAS involved in the notorious murder of the 'Princes in the Tower', according to a Yorkshire history professor.

Prof Tim Thornton of the University of Huddersfield says 'clear evidence' has come to light to implicate Richard in the murders.

Richard has long been held responsible for the murder of his nephews - the young King Edward V and his brother Richard, Duke of York, dubbed ‘the Princes in the Tower’ - in a dispute about succession to the throne.

The pair were held in the Tower of London, but disappeared from public view in 1483 with Richard taking the blame following his death two years later.

It has become one of the most enduring unsolved mysteries of all, stoked by references in Shakespeare’s play about the doomed Yorkist king and influenced by subsequent monarchs who were keen to paint their predecessor as a monster.

Defenders of Richard III, whose body was discovered buried under a car park in Leicester in 2012, have pointed to a lack of hard evidence to connect the king to the disappearance of the princes, who were aged just 12 and 9 when Richard took the throne in June 1483.

But writing in History, the Journal of the Historical Association, Prof Thornton says that there is now clear evidence to substantiate allegations made against the men identified as the boys’ murderer - and to connect them to Richard III.

The case against Richard has long rested on an accoubnt written by Sir Thomas More, the lawyer, statesman and philosopher, whose rose to become High Chancellor of England under King Henry VIII several decades after Richard III's death.

More's‘History of King Richard III’ was the first detailed account of the deaths of the princes. More named two men, Miles Forest and John Dighton, as the murderers, and claimed that they were recruited by Sir James Tyrell, a servant of Richard III, on his orders.

Until now, many people have questioned More's account, pointing out that it was written long after the event, and claiming it was ‘Tudor propaganda’ used to blacken the name of a dead Plantagenet king and to underline the right of the Tudors to be the ruling house of England.

Some even suggested that the names of the alleged murderers were made up by More. But Prof Thornton believes that More came to the right conclusion - and that he had inside knowledge.

Two of his fellow courtiers in Henry VIII's time were the sons of Miles Forest - one of the men More named as having killed the princes.

“This has been the greatest murder mystery in British history, because we couldn’t really rely on More as an account of what happened – until now,” says Prof Thornton.

“But I have shown that the sons of the chief alleged murderer were at court in Henry VIII’s England, and that they were living and working alongside Sir Thomas More. He wasn’t writing about imaginary people. We now have substantial grounds for believing that the detail of More’s account of a murder is credible.”

The mystery surrounding the princes has resonated for centuries, being revived in the 1670s when the bones of two boys were rediscovered in the Tower of London, and again in the 1930s when the remains, which had been reburied in Westminster Abbey, were scientifically reexamined.

The discovery of Richard III’s body under a car park in Leicester in 2012 also reignited interest in the controversial monarch, with some historians questioning whether he has deserved his notoriety. And the recent announcement of a new film about the rediscovery of Richard, written by Steve Coogan and Stephen Frears, shows that interest in the controversial monarch is as strong as ever.