Gyles Brandreth wanted to show Queen Elizabeth’s “inner mind” in his new book.
The 77-year-old author had known the monarch – who died in September aged 96 – since she was 20 and recently released 'Elizabeth: An Intimate Portrait’, and he explained his idea to write the biography stemmed from a phrase in a letter written by Elizabeth I to Edward VI.
He said: “Two days before she did, I was in the Elizabeth Room in the royal library at Windsor Castle.
“I saw a portrait of Elizabeth I, which she’d sent to her brother Edward VI and with it a letter saying how she regretted that she could not show him her inward mind.
“That’s when I thought, ‘This is my challenge’.
“Everyone knows what the queen looks like, she’s one of the most painted and photographed women in the world.
“But could I reveal what she was really like, her inward mind?
“This was my ambitious task, to show her extraordinary personality, her sense of humour, and why she became who she was.
“It was meant to be for her centenary, the whole story.”
The former MP was particularly keen to paint a picture of the queen’s younger years, for those who only remembered her as “a grandmother”.
He said: “Youngsters like my seven grandchildren only saw her as a grandmother, an elderly lady.
“They didn’t realise what a glamorous person she was.
“My favourite photo of her, taken by Cecil Beaton at Buckingham Palace when she was 16, is the one where she’s wearing a cap.
“It’s very glamorous and you can see how the Duke of Edinburgh fell for her.”
According to Gyles, the queen had been aware for years that he was writing a book about her.
He told Britain's HELLO! magazine: “At one event the Duke of Edinburgh teased, ‘You know he’s writing about you? He’s going to cut you up into little pieces.’
“The queen looked quite alarmed, so I reassured her that it would be respectful and admiring. ‘If you believe that, you’ll believe anything’, grinned the Duke.”