Charles Spencer has paid tribute to his "extraordinary" sister, Princess Diana, ahead of his "personal" new book release about the late royal.
The Earl, 62, who lives at Althorp House in Northamptonshire, said it was an "amazing" moment to hold the physical copy of Swan Song: Diana My Sister for the first time, ahead of its publication on 22 September.
The memoir is described by publisher Penguin Random House as "the most intimate, loving and honest portrait yet of his sister" and will contain "many revelations that will draw considerable attention".
It is reportedly set to cover the late Princess of Wales's 15-year marriage to the now-King Charles, their divorce, and the period leading up to her tragic death in a car crash in Paris in 1997.
© Instagram / @charles.earl.spencerWriting on social media on Friday, Charles said: "Always an amazing, and exhilarating, moment for an author to hold the first physical copy of a new book - and even more so for me with ‘Swan Song’, the most personal of the ten books I’ve written over the past three decades.
"At heart, this is a brother’s simple tribute to an extraordinary sister."
It will mark the first time he has spoken at length about his sibling and comes ahead of the 30th anniversary of her death next year.
The Earl, who recently married his fourth wife, Cat Jarman, in May, will also narrate the audiobook.
Charles Spencer's eulogy for Princess Diana
During Diana’s funeral at Westminster Abbey in 1997, Earl Spencer famously delivered a passionate eulogy, with a pointed reference to her "blood family".
Born into the aristocratic Spencer family in 1961, Diana married the King, then Prince of Wales, in 1981 and had sons Princes William and Harry. The couple divorced in 1996.
The Earl frequently shares memories from their childhood and occasional pictures of her resting place on social media, but, up until now, has not addressed what happened at length.
© Tim GrahamAnnouncing the book back in August, he said: "With the 30th anniversary of Diana’s tragic death on the skyline, I’ve been inundated yet again with requests for interviews about my sister.
"This has convinced me to write down my own thoughts and memories, once and for all, rather than having the discomfort of again reading the opinions of others, many of which are based on untruths that have become accepted over time.
"The aim of this book is to tell the truth about Diana from her brother’s perspective, just as I attempted to do when speaking at her funeral."
© WireImageHe added: "As with my eulogy, I want to speak on Diana’s behalf and do so in an openly positive way."
Remembering Diana on the anniversary of her death
On 31 August, the Earl took to social media to mark the 29th anniversary of Diana's death.
Sharing a short but moving tribute, alongside photographs of Althorp, he wrote: "31 August. My least favourite day."
A closer view of the photographs showed the Spencer family crest on a flag flown at half-mast, a traditional symbol of mourning.
Earlier this year, he revealed how "fundamentally unhappy" he feels when it comes time to mark the anniversary.
Charles and Diana grew up at Park House on the Sandringham Estate in Norfolk, moving to Althorp in 1975. They also had two older sisters, Jane and Sarah.
Diana would have turned 65 in July this year.
