EXCLUSIVE: Why Princess Diana's Brother's New Memoir is 'Set to Be a Best-Seller'
Princess Diana's brother's new memoir was tipped to become a best-seller.
Aug. 24 2026, Published 5:30 a.m. ET
Charles Spencer's new memoir about his sister, Princess Diana, is set to become a best-seller, with publishing insiders exclusively telling Radaronline.com its deeply personal secrets and previously untold revelations will fuel huge public demand when it arrives next month.
Spencer, 62, will publish Swan Song: Diana My Sister on September 22 – 29 years after Diana died in a Paris car crash aged 36.
Charles Spencer authored a new memoir about his sister, Princess Diana.
A publishing source told us: "There is enormous anticipation because Charles has memories nobody else can possibly possess. The secrets he is preparing to reveal about Diana, their family and the extraordinary pressures surrounding her life are certain to make this a best-seller.
"Readers have heard countless versions of her story, but never this one from the brother who grew up beside her."
Charles Spencer's Diana Secrets Revealed
Spencer wrote the memoir ahead of the thirtieth anniversary of Diana's death.
Spencer said he decided to write after receiving repeated interview requests ahead of the 30th anniversary of Diana's death.
He said: "With the 30th anniversary of Diana's tragic death on the skyline (next year), 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."
Spencer added his Swan Song book aims to "tell the truth about Diana from her brother's perspective, just as I attempted to do when speaking at her funeral."
He added: "As with my eulogy, I want to speak on Diana's behalf and do so in an openly positive way."
At Diana's 1997 funeral, Spencer made an emotional pledge concerning her sons, Prince William, now 44, and Prince Harry, 41.
He said: 'I pledge that we, your blood family, will do all we can to continue the imaginative
A Brother's Emotional Funeral Pledge
Spencer promised to protect young Prince William and Prince Harry after her death.
Spencer famously delivered a passionate speech at Diana's funeral in which he referred to his sister's "blood family" and promised to look after her sons William and Harry.
He declared as the farewell was watched by billions of royal fans worldwide on TV: "I pledge that we, your blood family, will do all we can to continue the imaginative way in which you were steering these two exceptional young men so that their souls are not simply immersed by duty and tradition but can sing openly as you planned."
Diana was buried on an island on Spencer estate, Althorp, in Northamptonshire.
A Personal Tribute To A One-Of-A-Kind Dynamic Character
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Daniel Bunyard served as publishing director for Penguin Random House UK.
He added about his upcoming tome: "I hope this book will be of interest to the many who still cherish the memory of Diana when she was alive, and 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 better place, despite exiting the stage while still so young."
Daniel Bunyard, publishing director at Penguin Random House UK, said: "Charles Spencer is both a loving brother and an acclaimed memoirist as well as a celebrated historian, and all these facets are brought together in Swan Song. "While these pages contain many revelations that will draw considerable attention, readers will find, for the first time, but also for all time, a fitting tribute to the beloved woman who was Princess Diana."
