Princess Eugenie turned 30 on March 23, and her grandmother, Queen Elizabeth, led the birthday tributes.
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The Royal Family Instagram account shared a snap of the Queen, 93, and her granddaughter smiling together on Maundy Thursday in April last year.
The Queen paid a special tribute to her granddaughter in the caption.
"Wishing Princess Eugenie a very Happy Birthday! Her Royal Highness is The Queen's 6th grandchild. Today she turns 30," it read.
"This [photo] was taken in 2019 when The Princess joined her grandmother at a Maundy Thursday Service at St George's Chapel in Windsor."
Eugenie's mum, Sarah Ferguson, the Duchess of York, also took to social media to wish her daughter a happy birthday.
"My favourite photograph just for her mum on her wedding day .. and my little girl is 30 today and Happy Birthday my little magic dust," she wrote, alongside a pic of Eugenie on her wedding day.
Eugenie took to Instagram later in the day to thank her fans and followers for their well wishes.
"Thank you for all the wonderful birthday messages. XX 💋" she wrote, alongside some throwback photos of herself as a baby and a young child.