A never-before seen photograph of the late Diana, Princess of Wales has been shared today on what would have been her 44th wedding anniversary to King Charles – who was Prince of Wales at the time. Taking to Instagram on Tuesday, Charles, Earl Spencer, shared a picture of himself and his sister at their childhood home.

The siblings, who were believed to have been close, spent the majority of their childhood at Park House on the Sandringham estate. They stayed at the home until 1976, when they then moved to Althorp House, where Charles Spencer still lives.

Sharing a photograph of the pair as children standing in their swimming costumes beside the family’s home pool, Charles wrote: “A long ago summer, by the swimming pool at our childhood home, Park House, Sandringham – Diana and I both proudly showing off our swimming badges (sewn onto our swimming costumes).”

He continued: “These were awarded (sparingly) by Mrs Lansdowne, a fairly terrifying but very gifted swimming instructor, who came to stay each year.

“We were never out of that pool.”

Since Diana’s tragic death in 1997, Charles, 61, has shared small insights over the years about his royal sister and their connection.

Speaking on Loose Men earlier this year, Charles said: “After Diana died, I would think I must ring her and tell her something, because we shared the same sense of humour, and you just realise of course that’s not going to happen.”

He continued: “And then actually, as your family naturally folds in on itself, you lose your parents.

“I have two sisters I adore, they’re quite a lot older than me, so I don’t have, I don’t share my childhood with anyone anymore.

“And that’s a great loss that you can never really put right.”