Princess Eugenie's Revealing Instagram of Her Dad Breaks Royal Rule

Princess Eugenie just broke royal protocol when she posted a picture of her father.

On Sunday, Princess Eugenie took to Instagram to share a photo of her father, Prince Andrew, during the Trooping the Colour ceremony, but the Royal Family member also broke a royal rule by showing a part of Buckingham Palace that typically is not shown to the public.

"A wonderful and proud day celebrating Her Majesty's birthday and @hrhthedukeofyork for his first Trooping the Colour as Colonel of the Grenadier Guards," the 28-year-old captioned the image of her father dressed in full military regalia.

The image, shared with her more than 200,000 followers, offered the public a rare inside glimpse of the private hallway in Buckingham Palace, the walls painted a light blue as a royally red carpet stretches the length of the floor. The walls are adorned with several large paintings, and a number of busts stand on pedestals near the floor-to-ceiling windows.

Eugenie's followers were quick to point out that this particular section of the Palace was one they had not previously seen.

"Oh my goodness...is this inside Buckingham Palace?! Beautiful!" one person commented.

"Great picture! And thank you for a shot of that gorgeous hallway in the Palace," another wrote.

Princess Eugenie remains one of the only members of the British Royal Family to have an Instagram account, as her cousins Prince William and Prince Harry, along with their wives, Kate Middleton and Meghan Markle, are prohibited from having social media accounts due to their status as working royals.

Princess Eugenie, along with her sister Princess Beatrice, however, are not considered to be working royals despite being princesses of the blood, as evidenced by the fact that they are not featured on the royal family's royal.uk website. Instead, Eugenie works as a full-time associate director at London art gallery Hauser & Wirth.

Eugenie, 28, launched her Instagram account in March and has used it to share photos of events that she attends as well as throwback photos of herself and sister Princess Beatrice.

The royal sisters, who infamously adorned their heads with bizarre fascinators for Prince William and Kate Middleton's 2011 nuptials, left social media users disappointed when they failed to wear equally bizarre fascinators to Prince Harry and Markle's May 19 royal wedding. Beatrice's 2011 pale pink silk bow hat, which matched her Valentino couture dress, was so popular that it ended up drawing in $130,000 in an auction to raise money for the Little Bee Initiative.