EXCLUSIVE: Why Charles Spencer's Princess Diana Memoir 'Won't Shake the Monarchy'

King Charles can weather the storm unleashed by Charles Spencer's explosive Princess Diana memoir because the monarchy has survived far greater crises, royal sources have told RadarOnline.com – despite damaging allegations about the King's behavior after his former wife's death.

Spencer, 62, will release Swan Song: Diana, My Sister on September 22, almost 30 years after Diana died aged 36 in Paris.

The book has already triggered an extraordinary dispute with Charles, 77, after Spencer alleged the then-Prince of Wales made a dismissive remark about Diana while they argued over her funeral arrangements.

A royal source claimed: "These allegations are deeply personal and inevitably painful, but there is a distinction between causing a major controversy for individuals within the Royal Family and threatening the monarchy itself.

"The institution has endured family disputes, abdication, scandal and enormous social change, and it will weather this storm. The monarchy is not going to be shaken by one book."

Spencer alleges Charles told him in the wake of Diana's death: "Rest assured, we'll forget her soon enough."

Buckingham Palace responded unusually forcefully to the accusation, saying: "While we do not comment on books as a matter of principle, His Majesty is mindful that the pain of fraternal grief can cloud reason, affect judgment and colour memory in ways others do not recognize, even many years after such a loss."

Spencer has stood by his account, describing the conversation as "monstrous" and saying he told friends and relatives about it at the time.

Another royal insider claimed: "There will undoubtedly be headlines and uncomfortable questions as further extracts emerge, but memoirs have been creating royal crises for generations. The Palace view historically has been that attention eventually moves elsewhere while the working monarchy continues."

Royal memoirs have repeatedly caused upheaval.

Marion Crawford, former governess to Princess Elizabeth and Princess Margaret, published The Little Princesses in 1950, while Edward VIII's autobiography, A King's Story, appeared the following year.

Decades later, Andrew Morton's Diana: Her True Story caused a sensation with Diana's cooperation, while Prince Harry, 42, generated worldwide headlines with his 2023 memoir Spare.

Another source familiar with the royal household said: "The monarchy's strength has always depended less on winning every argument than continuing with its public duties. That is why engagements, charities and ceremonial responsibilities continue regardless of whatever controversy is dominating the newspapers."

Charles has continued his official program while the dispute over Spencer's book has intensified, including hosting technology leaders at Dumfries House for discussions about artificial intelligence.

Harry has similarly continued public appearances, attending the Invictus Spirit Awards in London following his return to Britain.

Spencer has said his purpose in writing Swan Song is to record his own memories before the 30th anniversary of Diana's death.

He said: "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."

Spencer added: "I hope this book will be of interest to the many who still cherish the memory of Diana when she was alive."

Diana became one of the world's most recognizable public figures after marrying Prince Charles in 1981. The couple had two sons, Prince William and Harry, before separating in 1992 and divorcing in 1996.

Diana became celebrated for her humanitarian work, notably campaigning against landmines and challenging stigma surrounding HIV and AIDS.

Her turbulent private life and relationship with the royal family also attracted intense global scrutiny.

Diana was 36 when she and Dodi Fayed, 42, were killed following a car crash in the Pont de l'Alma tunnel in Paris on August 31, 1997, prompting worldwide mourning.