Sarah Ferguson has shared a revealing insight into her relationship with the Queen.
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Sarah was married to the monarch's second son, Prince Andrew, from 1986 until 1996 and together they share daughters Princess Beatrice and Princess Eugenie.
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Following the royal couple's divorce, Sarah maintained a close bond with her mother-in-law.
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This week, Sarah spoke at the Henley Literary about her Mills and Boon novel, A Heart for a Compass. And she let slip her nickname for the late Queen, who passed away on 8 September.
Sarah held her late mother-in-law in great regard
"It's been all my life that I've known the boss and there's no one like her," the Duchess said, via the Telegraph. "I wouldn't do anything unless the boss gave me her blessing though, and still to this day, I think about that."
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She continued: "When we wrote the book, I gave it to the boss and I said, 'You don't need to read it.'
They continued to be close - even after Sarah's divorce
"But I think she was so proud that we did it. And that's just huge for me. She was just very, very special."
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Sarah's first novel, historical romance Her Heart for a Compass, was released last year. It tells the story of Lady Margaret Montagu Douglas Scott and how 'one act of rebellion costs her place in society'. Her second book, A Most Intriguing Lady, is set to be released in February 2023.
Sarah moved royal fans when she shared her poignant tribute to the Queen last month.
Sarah paid a loving tribute to her late mother-in-law
She touched on their special bond, writing: "I am heartbroken by the passing of Her Majesty the Queen.
"She leaves behind an extraordinary legacy: the most fantastic example of duty and service and steadfasttness, and a constant steadying presence as our head of state for more than 70 years. She has given her whole life selflessly to the people of the UK and the Commonwealth.
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"To me, she was the most incredible mother-in-law and friend. I will always be grateful to her for the generosity she showed me in remaining close to me even after my divorce. I will miss her more than words can express."
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