The sweet but simple message read: “We love you, Papa. Happy Father’s Day [pink-heart emoji] G, C & L.” Princess Kate is said to have taken the shot during a visit to Norfolk last month.

The expert went on to explain why William and the children had their backs to the camera. She told the Mirror: “Photographed from the back view, they avoid actually communicating with the camera. It suggests this is an intimate and loving moment caught rather than a ‘show pony’ one posed to please the viewer.”

Expert Judi also revealed George has taken on a protective stance. She explained: “George and Louis are clearly growing up fast though and getting to the age where they want to show independence rather than joining the kind of pile-on pose they’ve enjoyed in the past.”

Judi also told the Sun, that the picture reveals both an unusual insight into the Cambidge’s family life, and Prince William seemingly moving away from royal tradition in favour of a more informal relationship with his children.

It comes a few hours after William posted a touching Father’s Day tribute to his “Pa”, King Charles with a nostalgic photo taken 40 years ago.

Also taking to the Prince and Princess of Wales’s social media accounts, William had shared a sweet picture of himself aged two playing football with King Charles. With William being born in June 1982, the adorable picture would have been taken in 1984.

The picture comes just one day after William joined his father at this year’s Trooping the Colour, the annual royal event which marks the monarch’s birthday.