Prince William and Prince Harry are twinning in an adorable throwback photo with Princess Diana.

The Duke of Cambridge shared an intimate photo of him with his younger brother, Princess Diana and cousins Peter Philips and Zara Tindall to celebrate 999 Day on Instagram. In the snap, both Prince William and Prince Harry are wearing sky blue uniforms while wearing hats.

Peter is on the wheels while Zara stands beside Prince Harry. Prince William is seated at the back of Peter while holding the pole and his headgear. The four royals look ready to respond to an emergency call. Meanwhile, Princess Diana appears to be looking after them on the side.

The royal fans who saw the post were delighted to see the photo. Many of them were happy because the snap gives those in emergency services a recognition.

“Emergency services don't get the recognition they deserve. Well done for highlighting them,” one wrote.

“I think as a child just about everyone of us has wanted to be a policeman/policewoman firefighter. So nice to see all the emergency personnel being supported today,” a different royal fan opined.

Meanwhile, another netizen said that it was the first time he noticed a picture of Prince William and Princess Diana together on the Kensington Palace profile and it’s “humble and moving.”

“I know it’s silly, but I’m glad you updated this with Diana’s name mentioned,” another netizen wrote.

A different user said that the snap is the most beautiful photo of the four cousins and Princess Diana. Although Zara and Peter are not working royals, they are very close to the Queen and Prince Charles as well as to Prince Harry and Prince William. The Cambridges’ kids are also close to their aunt Zara and uncle Mike Tindall.

A few months ago, Prince William and Kate Middleton were spotted enjoying an outing with Zara and Mike. Prince William had his goddaughter Mia Tindall on his shoulder while Prince George perched on Mike’s shoulder. Later that day, Prince George and Zara were photographed hugging and giving each other a high five. 

Princess Diana, Prince William, Prince Harry Pictured: Princess Diana, Prince Harry, Prince William gather for the commemorations of VJ Day, 19 August 1995, in London. Photo: Getty Images/Johnny Eggitt/AFP