The fact that it's 21 years after the much-loved Princess of Wales died in a horrific vehicle crash in Paris and 26 years since the royal couple's separation was announced to the British public by then Prime Minister John Major means it's all the more touching - and indeed, fitting - that a photo of the self-proclaimed "People's Princess" should be part of Charles' birthday celebrations. "I'm lucky to call Norfolk home and I love it there".
Other guests included newlyweds Princess Eugenie and her husband Jack Brooksbank - who tied the knot last month - and Charles' niece Zara Tindall.
One posted: 'I thought the photo of Charles with the beard and looking to the side was Harry!' Reports claimed that Cheryl was supposed to collaborate with Liam on the track - providing the female vocals that have now been sung by Lennon. William admitted that he underestimated the scale of the challenge; "I may have been too ambitious", he said.
Cheryl and Liam confirmed the end of their two-and-a-half year relationship in July 2018.
However, within years the pair embarked on a highly publicized affair and after both of their divorces came through, they officially began dating.
The duo are parents to son Bear Grey Payne, who was born in March 2017. Cheryl has candidly spoken about her split from Liam while promoting her comeback to the charts in recent weeks. Smiling happy is a happy family, right?
Here's more on why she wasn't in that important photo, plus what we know about the state of Queen Elizabeth II's health and what the palace believes she will die from.
It wasn't all bad news, however.
She further revealed she's never completed a marathon, with her nail-biting becoming incessant when she's stressed or on a flight experiencing turbulence.
William paid tribute to Charles, saying: "His passion for the environment and the natural world is something I want to repeat in the way I raise George, Charlotte and Louis".
"They are family, friends and ever-faithful companions and, just like anyone else with a passion for dogs, I can't imagine life without them", she said.
Taking to her profile, Tweedy posted the name of U.S. singer Ariana Grande's new breakup anthem "thank you, next". It's catchy and it's fun.