Sharing three beautiful photos of the Princess Royal to celebrate her milestone special day, one, in particular, appeared especially meaningful.
WATCH: Princess Anne's most memorable moments
The sweet image sees Kate and Anne sharing a giggle as they stand on the balcony at Buckingham Palace. Alongside an official portrait of Anne, which was released alongside two others ahead of her big day, there was also a photo of her and Prince William.
Captioning the post on the Kensington Royal Instagram account, it read: "Wishing a very happy 70th birthday to Her Royal Highness The Princess Royal!"
Kate Middleton shared this throwback with Princess Anne
Fans were delighted by the photos and rushed to the comment section of the post to wish Princess Anne well. "Beautiful photos, happy 70th birthday to the Princess Royal. I bet she is an amazing aunt," wrote one.
Another added: "Happy Birthday to a very hard-working, humble Royal." And a third said: "Lovely photos. Happy birthday!"
The Duke and Duchess of Cambridge marked Princess Anne's birthday on Saturday
The Princess - who lives at her private Gloucestershire home with her family - is spending her birthday sailing along the West Coast of Scotland with her husband, Vice Admiral Sir Tim Laurence.
Plans for a big family celebration were hampered by the Covid-19 outbreak, as Princess Anne's son-in-law Mike Tindall revealed earlier this week. But he told the BBC: "I'm sure we'll do something as a family to celebrate her 70 amazing years.
"She's just an incredible woman in terms of how much work she can get through in the year. We will be doing something. As yet, I don’t know whether she knows, so my lips are sealed."
For her birthday, the hard-working royal was treated to a very special gift by The Ministry of Defence, which announced honorary Army and RAF promotions for the Princess in recognition of her "invaluable contribution and commitment to the military".
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