On the November morning in 2019 when Prince Andrew recorded his bombshell Newsnight interview, Sam McAlister was on a chair 15ft behind him in the south drawing room at Buckingham Palace. The interview was conducted by presenter Emily Maitlis, but it was McAlister who’d spent months negotiating the encounter and she sat there carefully noting the prince’s slightly too small chair and the nervous tapping of his left foot.

But as his revelations poured forth — that he was too honorable to disown his pedophile friend Jeffrey Epstein; that he couldn’t sweat due to his Falklands combat experience; that he couldn’t have had sex with his accuser, Virginia Giuffre, in 2001 because he was at Pizza Express in Woking and he couldn’t remember a “positive act” (sexual intercourse) — McAlister soon noticed something else. When she gets anxious, she says, she tends to get a bit flushed and sometimes gets a nervous click in her throat. Her heart was racing. There was the tick. And out of nowhere she felt a mad impulse to… stop him talking.