Althorp House has long been in the Spencer family, and Charles, the 9th Earl Spencer, has shared a black-and-white photo of his grandparents at the majestic property – which is where he grew up with Princess Diana.
SEE: Princess Diana's regal upbringing in stately home with 550-acre estate
The unearthed photo, posted on Charles' Instagram account, shows his grandmother and grandfather sitting around an outdoor table as they ate their afternoon tea. It was surrounded by a wooden bench and two wicker chairs, which were positioned on a patio just outside a huge window.
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"My grandparents enjoying their tea ‘al fresco’ at Althorp, in 1944. Photograph taken by my father whilst on leave from military training," he explained.
It may have been taken 17 years before the late Princess of Wales was born, but Charles' followers were quick to point out the similarities between Diana and her grandmother.
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Charles shared a photo of his grandparents at Althorp
"The Diana head tilt," wrote one, and another added: "Wow this is an amazing photo. Your grandmother reminds me so much of Diana."
A third remarked: "I see where you and Diana got the tilting of the head from," and a fourth recognised the family resemblance with Charles' daughters: "Your grandmother is very beautiful and looks very much like your daughters."
Fans pointed out that Diana had the same head tilt as her grandmother
Diana, Charles and their siblings were raised at the Northamptonshire country house, and it was in fact the location where Diana's sister Sarah Spencer introduced her to the Prince of Wales.
The estate has been in the Spencer family for over 500 years
Althorp has 90 rooms and 550 acres, and features include: Wootton Hall, which has Italian marble checkerboard flooring where Princess Diana would practice her tap dancing; the Saloon, which makes a grand hallway; and a vast library which Charles revealed is his favourite room in the house.
The latter features wooden floors with three large patterned rugs, cream walls with endless shelves of books, and a selection of red armchairs and sofas.
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