Queen Elizabeth and Prince Harry have an incredible relationship, and they are actually very close. But there’s one thing about the Duke of Sussex that Her Majesty resents.

In the book “Harry: Life, Loss, And Love,” royal author Katie Nicholl revealed that the monarch is not particularly fond of her grandson’s beard. Prince Harry decided to grow one while he was in the military. But until today, he has grown attached to his facial hair.

According to the royal author, the Queen thinks that men should be clean-shaven at all times. But when Prince Harry decided to keep his beard at his royal wedding to Meghan Markle last year, Her Majesty was not able to do anything about it.

In one of the letters she wrote, the Queen expressed her delight over how much fitter Prince Harry looked before his royal wedding. However, she also noted the fact that her grandson still had his beard.

A royal source said that some members of the royal family loved Prince Harry’s beard. The Duke of Sussex’s cousin, Zara Tindall, even dubbed him as Prince Hairy.

“But the Queen soon let her displeasure to be known,” the royal source said. “She doesn’t mind royal men growing beards when they are away in the armed forces or out in the wild like Harry was in the Antarctic, but she expects them to be clean-shaven when they get home,” the source said.

Prince Harry Prince Harry, Duke of Sussex, Captain General Royal Marines, visits 42 Commando Royal Marines at their base in Bickleigh to carry out a Green Beret presentation at Dartmoor National Park. Finnbarr Webster - WPA Pool/Getty Images

Throughout the years, Prince Philip and Prince Charles have also been photographed with their thick beards. In fact, one of Prince Charles’ throwback photos made him look exactly like Prince Harry. However, the Queen has not particularly expressed her dislike of Prince Charles’ beard.

And when it comes to Prince Philip, Her Majesty even made fun of her husband’s beard. Prior to his return from a lengthy trip in 1957, the Queen learned that her husband grew his facial hair.

In order to make fun of him, Her Majesty commissioned her royal staff to put on fake whiskers when the Duke of Edinburgh arrives. “It was a comedy moment when the Queen and the Duke were finally reunited,” royal expert Robert Hardman said.

Queen Elizabeth and Prince Philip Britain's Queen Elizabeth II and Prince Philip, Duke of Edinburgh, react as they bid farewell to Irish President Michael D. Higgins and his wife, Sabina (not pictured), at the end of their official visit at Windsor Castle on April 11, 2014, in Windsor, United Kingdom. Leon Neal-WPA Pool/Getty Images