Royal fans have spotted Prince William's sweet tribute to his late grandfather Prince Philip in his office.
On his official Duke and Duchess of Cambridge Instagram account, William posted a short video to mark the upcoming release of the book Earthshot: How to Save our Planet.
William has written the foreword for the book, which is available later this month.
In the clip, William can be seen sitting down at his desk behind an old-fashioned-style typewriter, typing out his words.
The caption accompanying the footage says: "In my introduction to Earthshot: How to Save our Planet, the authoritative book of The @EarthshotPrize, I wanted to share the early conversations in 2018 that led to the Prize’s creation and the simple equation that captures my theory behind Earthshot: Urgency + Optimism = Action.
"The book will be available from 30th September."
And royal fans have spotted that behind the desk he sitting at, there is a sideboard with a beautiful framed photo of Prince Philip sitting in a horse-drawn carriage with a young smiling Prince George at his side
The picture, taken by Kate Middleton, was shared earlier this year in tribute to Philip, shortly after his death in April aged 99.
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It was taken in Norfolk in 2015, and William said at the time of releasing the photo that he would miss his grandpa.
He also added: "I will never take for granted the special memories my children will always have of their great-grandpa coming to collect them in his carriage and seeing for themselves his infectious sense of adventure as well as his mischievous sense of humour!"
Spotting the framed photo, one fan commented on the post: "Love the pic in the background!!!"
Another simply posted: "Prince Philip & Prince George in the background" with a heart emoji.
While another said: "Awww that background photo frame of his grandpa and his son is so" and followed it up with three heart emojis.
In the foreword of the new book, William pays tribute to Philip and dad Prince Charles, describing them as “pioneers in the environmental movement”, as he reveals his inspiration for launching his ambitious Earthshot Prize environmental project.
He also describes how “a wave of global pessimism” led him to the idea of creating a £50million prize fund over the next decade to find solutions to save the planet.
William writes: “The facts look terrifying, and I could see that this risked making people feel like they might as well give up. The global debate felt too complex, too negative, too overwhelming.
“It seemed to me, that there was a real risk that people would switch off; that they would feel so despondent, so fearful and so powerless, there was a risk that any real hope of progress would come to a halt.
“This despondency also jars with my own experiences, and those that inspired my grandfather and father to be pioneers in the environmental movement.
“Following in their footsteps, I have seen people all over the world face what seem like insurmountable challenges yet come together with collective ambition, and a can-do spirit, to find solutions to them."
