Earl Charles Spencer is set to give his perspective on his sister Princess Diana’s life in a revealing new book, ahead of the 30th anniversary of her death.

Diana, Princess of Wales, died aged 36 in August 1997, when a car she was travelling in crashed in Paris’s Pont de l’Alma tunnel. Her funeral was estimated to have been watched by more than two billion people around the world.

Spencer’s book, titled Swan Song: Diana, My Sister, will mark the first time that he has “spoken openly and at length” about his older sister, according to publisher Penguin Michael Joseph. The British peer is set to tell “the astonishing story of his life with Diana and the tragic week of her death”.

According to Daniel Bunyard, publishing director at Penguin Random House UK, the book will feature “many revelations that will draw considerable attention” but would also offer readers “for the first time, but also for all time, a fitting tribute to the beloved woman who was Princess Diana”.

He added that the book would be one of “historic importance” as well as “utterly unique in being written by Earl Spencer, from a vantage point of such intimacy”.

Earl Spencer said he had decided to write the book because, “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.”

He added that he’s hoping to “tell the truth about Diana” from his perspective, “just as I attempted to do when speaking at her funeral”.

The now-62-year-old delivered a eulogy at Diana’s funeral in September 1997, in which he described his sister as “the most hunted person of the modern age” and promised to protect her sons, Princes William and Harry.

“As with my eulogy, I want to speak on Diana’s behalf and do so in an openly positive way,” Spencer continued regarding his book.

“I would be delighted if those too young to remember her in her heyday feel – after reading this – that they ‘get’ who she really was: a one-off, dynamic character, full of love, charisma and self-doubt, who gave life a hell of a go, and left the world a far better place, despite exiting the stage while still so young.”

The book is set to be released on 22 September this year and will be translated into 12 languages.

Spencer has written 10 books about the his family, the royals and his life – one of the most recent being his 2024 memoir A Very Private School. In the book, he revealed that he was sexually abused as a child by a female staff member while at boarding school, which has left him with lifelong “demons”.