Andrew shared his memories of writing for Diana to mark the 20th anniversary of her tragic death.
Speaking on Saturday Night with Miriam on RTÉ One, Andrew told how he was shocked the first time Diana explained her eating disorders and suicide attempts in a series of cassette tape recordings.
Andrew explained: “I got taken to a working man’s cafe in North London. I put on these headphones, he pressed the button on the tape recorder and I was transported into this bizarre parallel universe where Diana was talking about her eating disorders… never heard of them.
“She was talking about her suicide attempts. These were desperate cries for help. It was like an initial kind of sampler of what she had to say. She was talking about this woman called Camilla.
“Nobody had ever heard of this woman and I’d been writing about the Royal Family and I thought I knew the Royal Family well. I thought I knew what was going on. Wrong again! I was transported into this world and for the next year or so had to try and make sense of it.”
He continued: “She felt absolutely disempowered. She felt like she was living a lie. She realised that the world was living the fairytale or looking at the fairytale of the Prince and Princess living happily ever after, but this was a postmodern fairytale. There was no happy ending.
“For her, she felt that she was a prisoner. She felt like she was being patronised by the men in grey, as she would call them inside the palace.
“Her husband was effectively living with another man’s wife, Camilla Parker Bowles, who was then married.
“She went out into the public and would meet the public, she’d be shaking hands and people would be smiling and cheering. She’d then go back to Kensington Palace… nothing. Silence.”
The former Royal reporter said that the impact of the book and her death made it easier for Prince William to marry a “commoner” and for Prince Harry to marry whoever he chooses because of how “Prince Charles was constrained by marrying a white Anglo-Saxon virgin”.
Asked why the world is still fascinated 20 years since her death, Andrew said: “It was the same impact as when JFK died. People remember where they were when she died. People watched her transform from a shy young girl to a sleek ambassador.”
Saturday Night with Miriam airs weekly on RTÉ One.