The image came in honour of Mother's Day on 14 March 2021, and showed August lying in the garden, giving fans a glimpse of the outdoor space of their house.
WATCH: Princess Eugenie welcomes baby boy with Jack Brooksbank
It looks as though there is a large lawn area, where August was pictured lying on a striped mat, with several bunches of vivid yellow daffodils planted around him.
The property is actually owned by Prince Harry and Meghan Markle, who are allowing Princess Eugenie and her husband Jack to use it while they are in the USA, in order to accommodate their growing family.
It is believed that during the Duke and Duchess of Sussex's time there, Meghan also planted several of one-year-old son Archie Harrison's lemon-yellow namesake Chrysanthemums. Archie was granted the honorary flower as part of a tradition which dictates that royal family members receive a namesake variety of the flower, in a nod to the blooms that decorated Westminster Abbey on Queen Elizabeth and Prince Philip's wedding day in 1947.
The Frogmore Estate covers 33 acres
Princess Eugenie's recent post only offers a look at a tiny area of the garden, though. In total, the Frogmore Estate comprises of 33 acres of private gardens, within Home Park, which adjoins to the Queen's second home at Windsor Castle in Berkshire. As well as Frogmore Cottage, the estate also includes Frogmore House.
When Eugenie and Jack moved into the house in November 2020, a friend told HELLO!: "Eugenie and Harry have always been close and they chat privately all the time. It was Harry who suggested she and Jack could use Frogmore Cottage because it is much bigger than their cottage at Kensington Palace. It is a case of one family member reaching out to another."
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