The letter, unveiled as part of an auction, also revealed the future princess’s hopes for her life.
Reflecting on her passion for dance, Diana wrote: “I have always wanted to and hope one day to get somewhere,” before adding that she was “off to find a place to dance.”
She also shared family news, writing her younger brother, Charles Spencer, then 14, is “loving boarding school and is now very tall and grown up for a 14-year-old.”
Valentina Borghi, a manuscripts specialist involved in the sale, said the letter stood apart from many Diana-related items that emerge at auction because it predated her entry into royal life.
She said: “It is refreshing to see something related to her life before she became Princess of Wales. Not many items from that period have been offered.”
Borghi added that collectors would likely be drawn to the insight the correspondence provides into Diana’s early years.
She said: “It is surely different to handle something that is related to her life before her marriage to Charles, and collectors will love it.”