Angela Levin spent 15 months following Prince Harry and told Nigel Farage that she's now worried about the next stage of his life.
The royal biographer told Nigel Farage on LBC: "I'm very worried for his future. I became very fond of him.
"I think he's quite charismatic, with this mischievous twinkle in his eye, and brilliant with people who need help."
"I do fear that if you want something and you actually get it, and it's all been very, very tricyk, you might feel euphoric at first.
"Then it dies down a bit and then you look back on it and you think about it and I think he will miss his family.
"I can't see how he can't miss his family. I think he'll want to show off baby Archie won't he? Let his cousins see him."
Farage said: "We all hope that it works for them. I think some of us are sceptical but we hope it works for them."
He asked: "Just how much harm has this episode done the Royal family?"
Levin replied: " I think it's done a lot of harm. I think it would be very hard to reconstruct it.
"Where it has been quite interesting is that it's induced huge support for the Queen. I mean, poor woman, she's 93, you can't you can't go against her still. She's amazing.
"Oh, but she's had a terrible year in 2019 and she could well have done with that."