Emily Maitlis, the former BBC journalist who conducted the interview, said the Duke had been “very jolly” when the cameras stopped rolling and clearly thought it had gone well.
But when the late Queen read the transcript hours before it was broadcast, she is said to have summoned her son to a meeting.
Maitlis told a new two-part Channel 4 documentary, The Problem Prince: “It was only on the Saturday when the Queen had reportedly read the whole transcript that he received a tap on the shoulder by his security detail.
“And they said, I think, ‘Sir, you might have to come with us’. It was after the Queen had seen what the interview contained that I think it dawned on her before it dawned on him.”
The fallout from the November 2019 interview was catastrophic for the Duke, having failed to express any regret over his friendship with Jeffrey Epstein, the convicted sex offender, or empathy for his victims.
Within days the Duke had been effectively sacked by his mother as a working member of the Royal family.
Virginia Giuffre, one of Epstein’s victims, later sued the Duke in a US court, alleging that he had sexually abused her on three occasions in 2001 when she was 17.
Sigrid McCawley, a member of Giuffre’s legal team, told the documentary she had been “thrilled” with the interview.
“You couldn’t have handed me a better present,” she added. “He said so many provably false things. It was just a roadmap to tear him apart.”
The Problem Prince charts the Duke’s rise and fall, from his days as a Falklands war hero, being dubbed “Randy Andy”, to his spell as trade envoy and subsequent downfall over his links to Epstein.
Maitlis and Newsnight “booker” Sam McAlister described how they eventually managed to clinch the interview after the Duke sought permission from his mother.
Meanwhile, Paul Tweed, a media lawyer and friend of the Duke, said he warned Amanda Thirsk, the Duke’s then-chief of staff, that the interview was a “bad idea” two days before it took place, but that she “abruptly” put the phone down on him.
“I said no way, no, no, no. That’s a bad idea,” he recalled. “You should not do it.”
He added: “At the back of my mind I thought: ‘Somebody’s going to stop this’.
“The Duke for better or worse had made his mind up that he was going to do it. The Duke made that decision on his own, against most advice.”
Maitlis said the Duke had asked during the negotiations: “Should I tell you why I can’t sweat?” as he sought to explain why Giuffre’s allegations against him were false.
She recalled: “He said, ‘the thing about adrenaline was after I was working in the Falklands, I lost the ability to sweat. And so actually what she [Ms Giuffre] says is completely not true.’
“And I remember thinking, wow, you know, if he says that, that’s it…”
Maitlis admitted that on the day of the interview, she was so nervous she had to shut herself in the lavatory at the palace to compose herself.
“I ended up wearing this military style jacket,” she said. I remember thinking, he’ll like a military coat, he’s a man of the armed forces, he’ll appreciate that.
“Then I started feeling really sick. I dived into the loo, I just wanted the door shut. I wanted to have two seconds of going ‘[deep breath] Where am I? What’s going on? Where is my head?’
“I had to deal with the fact that I was about to ask this man, this Royal, this Prince about his sex life. I was thinking how do I not mess this up.”
She said the Duke had arrived in the room before her “which really threw me”.
Maitlis added: “I was terrified about everything. I was terrified he wouldn’t want to talk about any of the things we discussed.”
However, when the Duke mentioned Epstein in his first breath, she realised her fears were unfounded.
“I kept on watching him thinking, he’s going to retract some of this, he’s going to pull some of it back,” she said.
In the event, the BBC team was astonished at how well it went for them. It was so clearly disastrous for the “euphoric” Duke that they feared palace staff would curtail it at any moment.
“We had got an interview the likes of which had never been seen before,” Maitlis said.
Maitlis also described how people had streamed into the room after the interview and she was invited to stay for “cinema night at the Palace”.