"Harry had this obsession with the media. He was so very unhappy."
According to the book, Harry would use the phrase "the palace syndrome": "when you won't fight the battles he wants, because you have been institutionalised".
"Giving in to the media was a key symptom of whether you had developed it.
"It was a constant test of loyalty: 'Are you going to protect me? Or have you just become one of them, who won't fight for me?' It was exhausting."
Low claims things only got worse after the now Duchess of Sussex came into his life.
"Harry's obsession with the media; his sense of frustration that he wasn't achieving everything that he could; his mistrust of the courtiers in the other households; the constant loyalty tests of his own staff: all of this was there before Meghan arrived on the scene.
"But after she turned up, it would get significantly worse."
It comes after Low also revealed this week that palace staff who worked for the couple now call themselves the "Sussexes Survival Club".
Staff felt they could "not escape" the couple's wrath and that there were "no lines or boundaries".
"It was a very difficult experience for many of them.
"Some people told me they were completely destroyed, they felt sick, they were shook."
