"Wishing a very happy birthday to The Prince of Wales," read the post from William and Kate's official Twitter account.
The Instagram account for Harry and Meghan, the Duke and Duchess of Sussex, soon followed suit, sharing a "previously unseen photo" of Charles smiling at the couple's infant son, Archie Harrison Mountbatten-Windsor, Sky News reported.
"Happy birthday to His Royal Highness The Prince of Wales – Sir, Pa, Grandpa!" the caption read.
Buckingham Palace also joined in, tweeting a recent picture of Charles, clad in a kilt, standing in front of the Castle of Mey in Scotland, as well as a baby photo of Charles with his parents, Queen Elizabeth II and Prince Philip.
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