Prince William's latest video with Princess Kate 'a new instalment in his war with Prince Harry'

In the video, that also featured rapper Snoop Dogg and football legend David Beckham, the royal couple said: "From all of us watching at home, congratulations to Team GB. Well done on all you've achieved - you've been an inspiration to us all."

However, the video featured Prince William sporting a new beard, which some said was a new instalment in the so called 'beard-wards.'

A source close to William told The Daily Beast: "It was a slight surprise to see William do a public video with the beard. It’s an unexpected new instalment of the beard wars."

The 'beard wars' refers to an argument centred around Prince Harry's beard that he grew in the tense run-up to the Duke of Sussex's wedding to Meghan Markle.

In his memoir Spare, Harry said he first ­­grew his beard while on an expedition in the South Pole and had come to rely on it as a "Freudian security blanket," adding that it made him feel "calmer." Prince Harry then claimed that he asked Queen Elizabeth II if he could keep it for his wedding.

He claimed that, while his grandmother was reportedly not overly keen on beards, she "understood." However, when he told his brother, Prince William "bristled" and said it was inconsistent with military rules, relevant as he was getting married in uniform, and precedent.

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Writing in Spare, Prince Harry then said: "When I informed [Prince William] that his opinion didn’t really matter, since I’d already gone to Granny and got the green light, he became livid. He raised his voice.”

William accused Harry of putting their grandmother "in an uncomfortable position," saying she had "no choice but to say yes." Harry said the argument "went on, in person, on the phone, for more than a week." The argument came to a head when Harry said: "he actually ordered me, as the Heir speaking to the Spare, to shave."

Friends of William have long cast doubt to Harry’s characterization of many events in his book but point out that William is in no position to publicly refute Harry’s claims.

One source, a former courtier who worked in the palace at the time of Harry and Meghan’s wedding, told The Daily Beast: “What the courtiers got so annoyed about with Harry is that over and over again he approached his grandmother personally to get special treatment and then he would turn around and say, ‘Well, Granny said so, so there.’"

Harry claims that the reason for the conflict over the beard was that William had come back from one assignment with the special forces "sporting a full beard, and somebody told him to be a good boy, run along and shave it. He hated the idea of me enjoying a perk he’d been denied."

One military source told The Daily Beast: "The point about the beard at the wedding is that serving members of the armed forces were not allowed to wear beards at that time.

"It’s a rule that goes back to gas masks. They wouldn’t seal properly on the face if you were not clean shaven. He went to granny and got special permission. William was completely right."