Princess Eugenie gave a sweet tribute to her "dear mumsy" Sarah Ferguson on the occasion of the British royal's 61st birthday.

Sharing a series of recent as well as throwback pictures of Sarah Ferguson to highlight her unique nature, Princess Eugenie said the Duchess of York is "one of a kind."

"Happy Birthday to my dear mumsy... You are one of a kind.⁣ There were too many pictures to choose from that show how completely unique you are," Eugenie wrote.

View this post on Instagram

Happy Birthday to my dear mumsy... ⁣ ⁣ You are one of a kind.⁣ ⁣ There were too many pictures to choose from that show how completely unique you are. ⁣ ⁣ 🎉🎊🎉🎊

A post shared by Princess Eugenie (@princesseugenie) on

Several of the pictures in the post were seemingly taken in the garden of the Royal Lodge, the Yorks' family residence in Windsor. There was also a recent selfie of the mother-daughter duo, along with an adorable throwback picture of Fergie with both of her daughters, Princess Beatrice and Eugenie. The famous picture in which the York princesses are wearing matching floral dresses was taken in 1992.

Sarah Ferguson took to her social media accounts to say thanks for the numerous wishes she received on her special day. In a video recorded near her beautiful dressing table, the mother-of-two said: "Hi everybody, I just wanted to say a very quick thank you so much for all of my wonderful birthday messages - 61, still red-headed and not out!"

The duchess is very active on social media and used it to keep young children entertained amid the coronavirus pandemic with her series "Storytime with Fergie and Friends."

Ferguson tied the knot with Prince Andrew in July 1986 at Westminster Abbey, but split in March 1992 and officially divorced four years later. However, the former couple has remained friendly and continue to live together at the Royal Lodge.

Eugenie once famously said about her parents' relationship: "They are the best divorced couple I know." Fergie herself told a radio station in 2016: "We've never really left each other."

Sarah Ferguson
The Duchess of York walked the catwalk during the Fashion For Relief show. Getty

Sarah is due to reach a special milestone in a few months, as she will become a grandmother for the first time when Eugenie and Jack Brooksbank welcome their first child in early 2021.