Prince Harry and Meghan Markle gave a touching nod to the late Queen Elizabeth II when naming their daughter.
The Duke and Duchess of Sussex named their second child, Lilibet, after her great-grandmother, believing this would be a wonderful surprise for the late monarch.
But author Tom Quinn claims Harry would have known that this would be perceived to many as "disrespectful and instructive" to the late Queen.
Lilibet Diana Mountbatten-Windsor, known as Lili, was born in California, America, on 4 June 2021 - and is seventh in line to the throne.
When Queen Elizabeth was a toddler, she referred to herself as Lilibet because she had difficulty pronouncing her own name.
The nickname ended up sticking and her close family members - the Queen Mother and King George VI, and her late husband Prince Philip - would use this sweet moniker when in conversation with her.
In his new book, Gilded Youth An Intimate History of Growing Up in the Royal Family, Mr Quinn wrote: "Meghan and Harry's second child, a daughter, was born in Santa Barbara, California, on June 4 2021.
"Even naming this child sparked a diplomatic scuffle. Hating even to think about the admittedly labyrinthine rules of protocol that surrounded the British royal family, Meghan and Harry called her Lilibet, apparently in the belief that it would be a wonderful surprise for her great-grandmother, Queen Elizabeth.
"That Harry did not have the sense to predict that this would cause trouble is beyond belief.
"He surely would have known that appropriating the monarch's beloved childhood nickname would be perceived by many as disrespectful and intrusive in a way that naming their daughter Elizabeth would have not been."
Mr Quinn claims some commentators saw it as a 'cynical' attempt to enhance their 'royal currency' when they were adjusting to life outside the royal family.
He went on to speculate the Queen's reaction to her great-granddaughter's name, juggling with the intended purpose behind it.
"The Queen may well have been upset that her grandson and his family laid claim to the intimate nickname that had always been very much part of the Queen's private life, but it is perhaps more likely that the flunkeys who surround the monarch and some of the starchier older royals were irritated by what they saw as a presumption," he continued.
"The late Queen may even have been touched by the gesture - a claim made by royal biographer Gyles Brandreth.
"But this point to a fundamental misunderstanding based on differences between American and UK culture."
He states Meghan would never have considered naming her daughter Lilibet to be anything but complementary toward the late Queen - and didn't expected it to come across as "impertinence" to the British public.
Meghan and Harry moved to America after announcing they were quitting the royal family and have been there ever since, except their brief farewell tour in the UK.
The couple went on to welcome their son Archie on May 6, 2019, and their daughter Lilibet two years later.
Tom Quinn's book, Gilded Youth An Intimate History of Growing Up in the Royal Family, is available from a number of online retailers including Amazon for £20.
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