The apparition has been haunting Windsor Great Park, where William and his family live, for centuries.
The ghost is said to be that of Herne the Hunter, the once-trusted friend of King Richard II in the 14th century who took his own life near Windsor Castle.
It is said the monarch’s top hunter hanged himself from an oak tree just half a mile north of Prince William’s Adelaide Cottage. He felt disgraced after being wrongly accused of poaching.
Many centuries on, people speak in whispered voices about Herne’s return to the forest near where he died, visits said to coincide with times of impending national disaster. Those forests are centred on the Prince and Princess of Wales’s cottage beyond the walls of Windsor Castle where dozens of locals claimed to have seen the demon.
Many books tell the spooky legend of Herne – immortalised by Shakespeare in his play the Merry Wives of Windsor in 1597.
A Windsor Castle source who has passed on the legend to tens of thousands of tourists to the castle over the years said: “Herne the Hunter is well known to the Royal Family. The original Herne’s Oak from which the king’s hunter committed suicide was replaced when it was chopped down in 1796.
“But Queen Victoria was so fascinated by Herne’s legend that she had his oak replaced
in 1863.
“The legend was passed down from royal generation to royal generation and both Prince William and Prince Harry are very aware of the apparition that roams the royal forest.
“In the dead of night, Herne has been seen riding his horse with antlers attached to his head rattling chains and seeking vengeance and justice on those who had cruelly wronged him.
“The tree where Herne hanged himself was just north of Frogmore House, which has been a royal retreat for over 300 years and home to the mausoleum where Queen Victoria lies.
“Prince William’s cottage is right next door to Frogmore House so Herne’s haunted oak tree is just a 10-minute walk through the forest or on ghostly horseback just a few minutes ride.”
It may have set pulses racing at last week’s Halloween celebrations. The source said: “Wills and Kate don’t need to scare their children with spooky Halloween tales or creepy costumes when they already have their own ghost said to pass by their front gates.
“He is said to blast his hunting horn and rattle chains as his horses’ hoofbeats are heard late at night galloping through the night as he seeks out the souls of those who wronged him.
“Windsor Castle has plenty of ghosts of course but Herne the Hunter is the most famous and on their first Halloween in Adelaide Cottage the children may have learnt of his legend. For sure it would be a spooky night for the family to stay indoors safe and sound.”