In private photographs published by the Royal Family as part of their efforts to honor Prince Philip, Princess Anne’s secret has been revealed.

The Princess Royal’s hair has been famously swept up in a beehive style for almost five decades, and no one has yet seen what it looks like when it isn’t.

However, a secret picture of Princess Anne and Prince Charles watching polo with their father at Smith’s Lawn in Windsor Great Park reveals that the princess’s hair was naturally blonde and wavy when she was younger.

Queen Elizabeth II and Princess Anne looking on as Prince Charles strokes an Ayrshire calf on the Balmoral Castle estate, Scotland. (Image: PA)

The Princess Royal is usually photographed in the same style she has worn since she was a young lady, whether she is attending a royal dinner at Buckingham Palace or walking her dogs in the grounds of her house in Gatcombe Park, Gloucestershire.

Anne has never deviated from the up do that was popular when she turned 18 in 1968, according to fashion experts throughout the years.

Anne, now 70, spoke about her hairdo when actress Erin Doherty, who portrays a youthful Anne in the Crown, said it took between 90 minutes and two hours to perfect in numerous interviews.

In one interview, the actress remarked, “It’s its own beast.”

“Literally, I would sit in the chair, people would come in and go and come in and go, and I sat still in the same place.

“But it was so necessary for her character because it felt like her hair and her fashion were the way that she was able to express herself in the confined, controlled environment that she grew up in.”

“Actually I read an article the other day about this, I don’t watch Netflix and The Crown, but the actress was talking about how long it took them to do their hair like I did,” Anne said of the Netflix program The Crown.

“And I’m thinking, ‘How could you possibly take that long?’ I mean, it takes me 10 or 15 minutes.”

Anne’s hairdo, which has gone in and out of style many times over the decades, has become so iconic that it is nearly as well-known as the wearer.

The Duke of Edinburgh sharing a joke with his daughter the Princess Royal (Image: PA)

For example, when Loose Women host Denise Welch stated on daytime TV that her daughter should urge her to change it up, it sparked a national discussion.

“I just wish Zara could say to her, ‘Mum why don’t you just get yourself a graduated bob,'” she added.

“I just thing she’d really suit a nice graduated bob.

“’I’m sure she’s not going to take advice from me, but I think she’d really suit it.”

The photo of a young Anne was shared as part of a short film clip on Prince Charles’ Clarence House instagram feed.

Princess Royal Anne can be seen with her hair down, which is a departure from her usual look.

Anne’s hair is naturally thick and wavy in all earlier photos of Philip and the Queen off duty in the 1950s.

Princess Royal with her father and brother at Smith’s Lawn, Windsor Great Park, where they were watching the Polo. (Image: PA)

“My father, for I suppose the last 70 years, has given the most remarkable, devoted service to The Queen, to my family and to the country, but also to the whole of the Commonwealth… My dear Papa was a very special person,” read a caption.

Later photos show her wearing it long and down and fashioned in the backcombed manner of the day when she was a young woman.

Half and half: Rare image of Princess Anne with long hair down (Image: mirrorpix)

Anne paid her respects to her father yesterday, walking with her brothers behind his coffin as it made its way to St George’s Chapel in Windsor Castle’s grounds.