And it's set to reveal never before seen images and stories about Queen Elizabeth II
Royal staff are expected to never disclose the secrets they may learn while working for the Queen and her family, so news that the Queen's personal dresser Angela Kelly has been given "extraordinary permission" to publish a book detailing their 25-year working relationship is a surprise.
The book, which is called The Other Side of the Coin: The Queen, the Dresser and the Wardrobe is due to be published by HarperCollins on 29 October. And marks the first time a serving member of the royal household has been given such permission.
In a 2007 interview with the Telegraph, Kelly described her conversations with Queen Elizabeth as that of "two typical women" adding: "We discuss clothes, make-up, jewellery.
"We [the royal dressers] are not treated like flunkies," she said. "It's not like that. The Queen treats us with real respect.
"I don't know why the Queen seems fond of me - because I don't give her an easy time! I do think she values my opinion, but she is the one who is in control.
"I do worry about her and care about her. But we also have a lot of fun together. The Queen has a wicked sense of humour and is a great mimic. She can do all accents - including mine."
Samantha Cohen, former Assistant Private Secretary to the Queen, said: ‘This book documents the unique working relationship between Her Majesty The Queen and the woman who has been her Personal Advisor and Senior Dresser for more than two decades: Angela Kelly.
"It gives a rare glimpse into the demands of the job of supporting the Monarch, and we gain privileged insight into a successful working relationship, characterised by humour, creativity, hard work, and a mutual commitment to service and duty.
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"Angela is a talented and inspiring woman, who has captured the highlights of her long career with The Queen for us all to share."
A spokesman for HarperCollins said: "The Queen has personally given Angela her blessing to share their unparalleled bond with the world. Angela Kelly is the first serving member of the Royal Household to have been given this extraordinary permission.
"Whether it’s preparing for a formal occasion or brightening Her Majesty’s day with a playful joke, Angela’s priority is to serve and support.
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"Sharing never-before-seen photographs – many from Angela’s own private collection – and charming anecdotes of their time spent together, this revealing book provides memorable insights into what it’s like to work closely with The Queen, to curate her wardrobe and to discover a true and lasting connection along the way."