Prince Harry should "take a leaf" from his great-great-uncle Edward VIII and write a memoir later in life without "bitterness" or "moaning", a royal expert has said.
The Duke of Sussex has reportedly signed a $20 million (£14.3 million) book deal and is working with ghost writer JR Moehringer on a memoir.
Royal expert Anna Pasternak has argued that Harry should "take note" of how his distant relative Edward VIII approached his own book, A King’s Story, The Memoirs of The Duke of Windsor, published in 1951.
That book - for which Edward was paid "£300,000 (roughly £3.5 million today)" - was also ghost-written, and was also not welcomed by the Royal family.
Ms Pasternak, writing in the Telegraph, said: "The Duke of Windsor and Harry also share, along with their love and loyalty to their dominant American wives, an ambivalence about their heritage."
She continued: "However, unlike Harry, who self-exiled from the Royal family 15 months ago, choosing love and family over monarchical duty, the Duke of Windsor waited 15 years before publishing his account of abdicating to marry Wallis Simpson. "
Edward VIII abdicated from the throne in 1936 after his plans to marry Ms Simpson, an American who was divorcing her second husband, caused a constitutional crisis.
He was a controversial figure. The couple visited Nazi Germany in 1937 against the advice of the UK government and met with Adolf Hitler.
Ms Pasternak quotes Edward on his waiting until "passions" had "cooled" before writing the book.
She writes: "In contrast with Harry's alleged book deal, the memoir was the last word that the Duke ever wrote on his life or the abdication. He died 21 years later.
"He did not detail his bitterness over his life in exile, nor his pain towards his unyielding family.
"Judging by his recent form, such restraint seems unlikely with the memoir that Harry will produce. If only the Duke of Sussex would take note.
"Once the royal drawbridges have gone up behind you, in literary terms, less is always more."
Prince Harry has had a strained relationship with his family since stepping back from his royal duties last year and moving to the United States with his wife Meghan Markle.
The couple sent shockwaves through the monarchy during a bombshell interview with Oprah Winfrey.
They accused unnamed members of the royal family of racism and Meghan shared how she had considered suicide.
Harry and Meghan welcomed their second child this summer, a girl they named Lilibet.
