Prince William commemorated an important milestone as he included his family, Kate Middleton and their three children for the occasion.

Kensington Palace on Thursday shared a special message from Prince William along with some rare photos of the Wales family meeting with Sir David Attenborough.

“As he turns 99 today, in his new film, Sir David has once again reminded us of the need to protect natural habitats – this time those beneath the ocean,” William wrote in his personal message. “He has dedicated his life to ensuring we understand the realities of what mankind is doing to the planet.”

The future king continued, “However hard hitting his message is, Sir David always leaves us with a sense of hope and optimism that all is not lost and this film is no different. We must act together, with urgency, to restore our oceans.”

He concluded with, “Happy Birthday, David” and adding a “W” at the end.

The message comes just a day after the Prince and Princess of Wales, along with their three children, skipped a key event at the Buckingham Palace.

On Wednesday, King Charles and Queen Camilla were joined by Princess Anne, Prince Edward, Sophie, Duchess of Edinburgh and the Duke and Duchess of Gloucester for the first garden party of the season.

The Prince and Princess of Wales were notably missing from the event. However, they had attended the tea party held in Palace following the VE Day fly-past on Tuesday. 

Prince George had made a special appearance as the young prince learned the ropes of royal duties.