Princess Diana
Princess Diana mixed up her wedding anniversary date. The Princess of Wales is pictured smiling while she meets well-wishers outside St Vincent’s Hospice on Nov. 2, 1996 in Sydney, Australia. Torsten Blackwood/AFP/Getty Images

Princess Diana often lived her life in the spotlight, but it appears there were times that her nerves got the best of her. Between 1989 and 1992 the Princess of Wales carried on a correspondence with British Vogue Editor Elizabeth Tilberis that now suggests she did not know the date of her wedding to Prince Charles.

Six of Diana’s handwritten personal letters are expected to be sold off by Swann Auction Galleries. However, during one of her exchanges following a photo shoot with the publication, Diana incorrectly reflected on her upcoming wedding anniversary.

In a letter dated for March 5, 1991, Diana appeared to forget the date of her 10-year wedding anniversary to Prince Charles due to the media build-up to the event.

“Alas, I fear that there aren’t going to be any photographs released for my birthday in July - there is too much of a build-up towards the 30th & 10 years of marriage ... I do feel terribly that there is far too much of this lady in the media,” she wrote.

However, Princess Diana’s wedding anniversary to Prince Charles was on July 29.

Aside from her flub, the Princes of Wales praised Vogue’s staff members and photographer Patrick Demarchelier for making her feel “relaxed” throughout her photoshoot. “Patrick ... was a dream & I hope he will be happy with the results!” Diana wrote.

Despite the noticeable error, a spokesman for the auctioneers revealed the purpose of the letters were to display the warm exchanges between Diana and Elizabeth.

“The correspondence sheds light on the growing warmth and friendship between the two as they collaborate on various Vogue shoots, detailing how much Diana clearly valued time spent with Tilberis and others.”