A retired British policeman recently revealed a hilarious incident involving Prince William, who was mistaken for an intruder at his grandmother Queen Elizabeth II's Sandringham estate.

The Duke of Cambridge was taking a late-night walk on the estate several years ago when he was chased by a police dog. PC Jon Chandler, who is retiring from the Norfolk Police after 30 years in service, recently recalled the incident in a conversation with the Eastern Daily Press.

"I had a particularly interesting night when I was walking my dog off the lead around the grounds and he chased after the future king of England. It was late at night and Prince William was walking towards the garages and the dog picked up his scent and went charging after him," Chandler told the outlet.

He added that luckily, the British royal who was "only young then" took the incident "in good jest," noting that it could have gone very wrong if the dog attacked him.

"It could have gone horribly wrong if he was bitten, but fortunately the dog did what it was supposed to do, and just stood back and barked at him. It was a memorable night," Chandler said.

Prince William is also quite fond of dogs, like many other members of the royal family. Unfortunately, William and Kate lost their family dog, a black cocker spaniel named Lupo, in November last year.

The Cambridges welcomed Lupo into their family in 2012, months after their royal wedding. The royal pup was also included in the family photo clicked after the birth of Prince George.

Interestingly, William is not the only British royal who was mistaken for a trespasser on the royal grounds. The Queen herself had a close call with a security guard who could have shot her after confusing her for an intruder during a late-night walk at the Buckingham Palace.

"Bloody hell, Your Majesty, I nearly shot you," the guard reportedly told her after realising his mistake, to which the monarch said: "That's quite all right. Next time I'll ring through beforehand so you don't have to shoot me."

Prince William
Prince William once joked that his dog Lupo would not be very good in the Spaniel (Reuters)