Princess Diana
Young Prince Harry tries to hide behind his mother Princess Diana during a morning picture session at Marivent Palace on August 9, 1988.Reuters

Princess Diana's private handwritten letters to former Buckingham Palace steward Cyril Dickman have surfaced online and talks about the relationship Prince Harry and Prince William share. The handwritten letters, photos, and signed Christmas cards, which were unearthed by Dickman's grandson, Matthew Dickman, will be hitting the auction block.

In one of her letters, Diana shared some of the intimate moments of her family between 1984 until 1993. She also described William and Harry's adorable loving relationship when they were kids.

"William adores his little brother and spends the entire time swamping Harry with an endless supply of hugs and kisses, hardly letting the parents near! The reaction to one tiny person birth has totally overwhelmed us and I can hardly breathe from the mass of flowers," a letter dated September 20, 1984, reads.

Princess Diana
Princess Diana holds her two sons Prince William, 6, and Prince Harry, 3, (front) as they pose during the mornings's picture session on August 9, 1987 in Palma de Mallorca, Spain.Reuters

In another letter, dated October 17, 1992, describing how mischievous Harry was, she wrote, "The boys are well and enjoying boarding school a lot, although Harry is constantly in trouble!'

"This is just to say a big thank you, Cyril, for thinking of us at this particularly happy time, with lots of love from, Diana," she said in one of the letters, which talked about Harry's birth.

Diana also wrote a letter for Dickman after the death of his grandmother in July 1993. "Thank you so much for your lovely letter concerning my Grandmother. Her death came as a great shock, but it has meant an enormous amount to receive messages of support such as yours. I often think of you and Mrs Dickman and hope that life is treating you kindly," she wrote.

Matthew will put all the handwritten letters for auction on January 5 at Cheffins' auction house in Cambridge. The letters are valued at $18,500.

"Cyril's grandson came in and said while he was going through everything he found all of these amazing letters from Princess Diana.The letters explained all different things - how Harry had been naughty at school and how Harry was adored by his brother who would not stop kissing him. It is incredibly rare to have letters from Princess Diana with such a personal touch to them," Dylan Mander, a specialist at Cheffins' auction house, said, according to Daily Mail.