Prince Harry's bombshell book will 'shake the monarchy to the core' and lay bare feelings towards Camilla... as he STILL hasn't publicly congratulated his stepmother on being next Queen

 Friends of Prince Harry have warned his no-holds barred book will lay bare his true feelings towards his step-mother Camilla and is likely to 'shake the monarchy to its core'.

The Duke of Sussex, 37, is set to publicly spill all on his relationship with his estranged family in an explosive £14.7million ($20million) memoir due to be published later this year. 

The Royal Family has been left deeply concerned by Harry's decision to secretly collaborate with Pulitzer-winning ghostwriter JR Moehringer on what his publishers described as 'the definitive account of the experiences, adventures, losses, and life lessons that have helped shape him'.

The Queen, Prince Charles and Prince William are said to have been completely blindsided by Harry's shock announcement that he has been secretly working on his as yet untitled memoirs for more than a year now. 

Royal experts had previously warned that the potentially explosive book could burn further bridges with the distant Duke and The Firm.

And sources close to the Duke of Sussex fired a warning shot on Saturday that is likely to send chills through the Royal Family as news of Harry's potentially explosive memoirs reappeared. 

His friends told the Mirror: 'If they think he's gone soft, they are mistaken. Just wait for the book to come out because that will shake the monarchy to the core.' 

The Duke of Sussex, 37, is set to publicly spill all on his relationship with his estranged family in an explosive £14.7million ($20million) secret memoir due to be published later this year 

Prince Harry had come under fire this week for seemingly ignoring the fact Camilla was bestowed the ultimate blessing by Her Majesty and will become Queen Consort

Initially, the prince did not make any public announcement, but breaking his silence four days later from his Californian mansion, he paid lavish tribute to his mother Diana's work on Aids and HIV

Prince Harry had come under fire this week for seemingly ignoring the fact Camilla was bestowed the ultimate blessing by Her Majesty and will become Queen Consort.

Initially, the prince did not make any public announcement, but breaking his silence four days later from his Californian mansion, he paid lavish tribute to his mother Diana's work on Aids and HIV.  

Source close to the prince say his recent silence 'speaks volumes' and they allege Harry still shares a frosty relationship with his stepmother. 

Harry's book, due to be published by Random House in late 2022, will likely tackle the brothers' frosty relationship with the Duchess of Cornwall, who last week was confirmed as the future Queen Consort.  

The Royal Family has been left deeply concerned by Harry's decision to secretly collaborate with Pulitzer-winning ghostwriter JR Moehringer on what his publishers described as 'the definitive account of the experiences, adventures, losses, and life lessons that have helped shape him'. Pictured: Camilla and Diana pictured together in 1980

The Duke's explosive memoir is expected to ­explore Harry's childhood, his time in the military and his marriage to American-born former actress Meghan Markle

Friends of the Duke explained to the Mirror: 'Although tensions have eased between the two of them over the years, it was more for a show of unity than a close relationship.

'There were big problems at the start but as Harry and his brother William aged and matured, things got better and they can now co-exist as adults. They were never close with her and they still aren't.'

It comes as The Mail on Sunday revealed Camilla would be crowned side-by-side with Charles in a slimmed-down Coronation celebration when the time comes. 

The Prince of Wales has already let it be known that he favours a leaner monarchy and his Coronation service – whenever it comes – is expected to set the tone for his reign.

Last week the Queen declared it was her 'sincere wish' that Camilla would be known as Queen Consort when, 'in the fullness of time', her son becomes King. 

The first draft of the manuscript, currently untitled, is said to be almost completely written and is due to be submitted in October 

Prince Harry has been working with Pulitzer-winning ghostwriter J. R. Moehringer

Prince Harry had come under fire this week for seemingly ignoring the fact Camilla was bestowed the ultimate blessing by Her Majesty and will become Queen Consort 

The Sussexes' radio silence on Camilla's announcement came despite a source claiming Harry had extended an olive branch to his father last month in a bid to heal their rift ahead of the Queen's celebrations.

He is expected to return to the UK for the Platinum Jubilee, which will see the country enjoy a four day bank holiday from June 2 to 5.

It is not known if Meghan Markle, 40, and their children Archie, two, and eight-month-old Lilibet, will be joining him. But royal aides are said to be concerned the memoir will be a one-sided account of the prince's experiences. 

And in further comments that are likely to concern the Palace, Harry's friends added: 'He has got lots to say. People think he's keeping a low profile to respect the family but it's not that.

'He's writing a book. He's got a multi-million-pound book deal and he's keeping a lot of his opinions for that. The memoir deal states that it should include personal details of personal and family arrangements.

'And it will be a really intimate take on his feelings about his family and what has gone in the breakdown of the relationship.'

The memoir is expected to ­explore Harry's childhood, his time in the military and his marriage to American-born former actress Meghan. 

At the time the book was announced last summer, Harry said of the memoir, to be published by Penguin Random House, will be written 'not as the prince' he was, but as the man he has 'become'.

He said, 'I'm writing this not as the prince I was born but as the man I have become.

'I've worn many hats over the years, both literally and figuratively, and my hope is that in telling my story - the highs and lows, the mistakes, the lessons learned - I can help show that no matter where we come from, we have more in common than we think.

'I'm deeply grateful for the opportunity to share what I've learned over the course of my life so far and excited for people to read a first hand account of my life that's accurate and wholly truthful.'

MailOnline approached representatives of Prince Harry for comment but has not yet received a response.