Charles ‘has a lifetime of secrets that’ll be…': Royal expert on Harry's memoir

King Charles-Prince Harry: Prince Harry's memoir titled ‘Spare’ is set to be released in January next year.

King Charles should be "very worried" about Prince Harry's upcoming memoir, a royal expert said claiming that the book will be "like a hand grenade lobbed right onto" Buckingham Palace.

King Charles: Meghan Markle, Prince Harry, Queen Camilla and King Charles attend the state funeral of Queen Elizabeth. (Reuters)

“King Charles should be very, very worried about Prince Harry’s new book. The duke has a literal lifetime of revelations, dirt and secrets to draw on, not to mention the Viking-sized battle axe he has to grind with his family,” Daniela Elser told The Daily Beast.

Prince Harry's memoir titled ‘Spare’ which is set to be released in January next year has promised readers "a firsthand account of my life that’s accurate and wholly truthful".

“What the 72-year-old can’t afford is to waste precious months or years trying to put out PR fires and having to figure out how to countermand another relative busily telling the world what a dismal human being he is,” the expert added.

The memoir is expected to shed light on Prince Harry's life, including the early years when he experienced of his father's marriage to Princess Diana and her tragic death.

UK media reports said that the book will also talk about King Charles' affair with Camilla and how it impacted Prince Harry and Prince William.