The royal couple always share pictures of their daughter's big day – which falls on 21 April – and this year was no exception. The latest snaps show the little princess smiling sweetly into the camera as she plays in the park.
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The pictures show that Isabella has an eye for style – just like her mum. Her blue gilet and print top are perfectly accessorised with a pretty floral headdress in the same shade. Pink trousers and shoes completed her look.
Princess Isabella – who shares her birthday with the Queen – spent her big day surrounded by family and friends.
Frederik and Mary organised a private party for their daughter, who enjoyed cupcakes and gifts with her siblings Christian, seven, and twins Vincent and Josephine, two.
Prince Joachim, his wife Marie and their eldest son Henrik were also at the party, and Queen Margrethe attended with her sister Benedikte.
Last week, Queen Margrethe celebrated her own birthday with a family appearance on the balcony of Copenhagen's Amalienborg Palace. Although the monarch was on fine form, it was her young grandchildren who stole the show.