Charles Spencer sparked a fan reaction on Tuesday with an incredible black and white family photo.
Taking to Instagram, the 58-year-old shared a striking picture of his late father, John, aged 16. In the touching image, Charles' father could be seen posing in front of Althorp dressed in military clothing.
WATCH: Princess Diana's place of rest is 'bewitching' in breathtaking video
Alongside the portrait, Charles penned: "My father in 1940, aged 16, standing outside an ivy-clad Althorp. Today would have been his 99th birthday."
Fans and friends raced to weigh in on the post, with one writing: "Lovely picture Earl spencer! You look so like your father!" whilst a second penned: "Awwww," followed by a blue heart emoji.
Charles' late father
"The Apple doesn't fall far from the tree," noted a third, and a fourth added: "God rest his soul," followed by the praying hands emoji.
Charles inherited Althorp following the death of his father in March 1992, at which point he also succeeded as 9th Earl Spencer.
He now resides there with his third wife, Karen Gordon. The couple were married in June 2011 and together share daughter Lady Charlotte Diana, ten. The Spencer family's ancestral home in Northamptonshire boasts 90 rooms and some 550 acres – and was where Princess Diana grew up with her three siblings, prior to her 1981 marriage to Prince Charles.
Charles shared a breathtaking painting of his mother
Charles' trip down memory lane comes after the ninth Earl shared a stunning portrait of his mother to commemorate her birthday – and the family resemblance is uncanny!
"Portrait of my mother, which stands in Althorp's Library," he said, before adding that the portrait is also: "Surrounded by pictures of 4 of her children. (The other - her son, John - died on the day he was born.)"
He went on to say: "My mother was born 87 years ago today, in Park House, Sandringham. On that very same day - 20 January 1936 - a few hundred yards away, in Sandringham House, King George V died. My mother died in 2004, when 68. Too young."
Like this story? Sign up to our HELLO! Mail newsletter to receive all the latest royal and celebrity news straight in your inbox.