Speaking to GB News, author Tom Bower, who released Revenge: Meghan, Harry and the War Between the Windsors earlier this year, said Harry was insisting his tell-all memoir be published in November.
"I'm told tonight that Harry is insisting that his book is published in November," he said.
Interviewer Dan Wootton was shocked by the revelation, saying: "You're kidding?"
"It's absolutely astonishing," the author continued. "Apparently the publishers are not too certain, but he says if they don't publish it's a breach of contract, that's what I'm told.
"It's extraordinary because, on the other hand, it fits the bill because Harry and Meghan's finances depend entirely on the book or Netflix and also I think they're convinced they're in the right and they want to get their own back and I think part of the problem of getting them to come out on that walk [at Windsor Castle] it was rare much because they can't decide whether they should appear or not.
"They didn't plan to be here for a funeral, they thought they were coming here just to visit to promote themselves."
Speaking on The Morning Show on Tuesday, entertainment reporter Peter Ford said the plan to publish the memoir in November was "quite a bombshell to drop just as they're doing the seating plan for the funeral".
Prince Harry did not get to see his grandmother one more time before her death, with him leaving to make the journey to Balmoral much later than his brother Prince William and other relatives.
According to The Telegraph, “Harry hadn’t even been called” while William was boarding his private jet with Prince Andrew, Prince Edward and Sophie, Countess of Wessex.
The publication reports that the royals didn’t expect the Queen to deteriorate so quickly, and William was summoned by King Charles as a Counsellor of State.
After Buckingham Palace had alerted the public that the doctors were "concerned" about the Queen, Harry rushed to Scotland, departing London at 5.35pm.
Unfortunately, the Queen’s death was announced at 6.31pm while Harry was still in the air. He didn’t arrive at the castle until 7.52pm.
In a statement on the website for the Sussex's non-profit organisation Archewell, Harry said the Queen was "globally admired and respected".
"Granny, while this final parting brings us great sadness, I am forever grateful for all of our first meetings—from my earliest childhood memories with you, to meeting you for the first time as my Commander-in-Chief, to the first moment you met my darling wife and hugged your beloved great-grandchildren," he wrote.
"I cherish these times shared with you, and the many other special moments in between."
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