This came months after Queen Elizabeth II's death and before the coronation ceremony of King Charles III.
Historian Rafe Heydel-Mankoo had also accused the Sussexes of grabbing the limelight when it should be on the King Charles III coronation, according to experss.co.uk reports.
"The thing is, of course, that this is supposed to be the first of a four book deal and we've had him almost blackmailing the Royal Family saying 'oh, well, I left the most sensational pieces out of the book," Mankoo said.
"Almost, 'If you don't engage with me and apologise, well who knows, maybe there will be a volume two to Spare'," he added as quoted by experss.co.uk.
Earlier, Harry had also spoken to Britain's ITV network in order to promote his book Spare, which contains details of personal emotional pain and sour familial animosities.
In the interview, he claimed that members of the Royal Family had gotten “into bed with the devil" in order to get positive tabloid coverage. Prince Harry also asserted that his family was "complicit" in his wife Meghan's pain and suffering.
He further alleged that his stepmother Camilla, the queen consort, had revealed private conversations to the media.
The Royal Family needed to learn and develop in order to be a part of the solution rather than a part of the issue, according to Harry, who also said that the experience was an example of unconscious bias rather than racism.
