Sir John Batten treated Diana in the early years of her marriage to Prince Charles when the newlywed was acutely aware he was seeing Camilla Parker Bowles.
But instead of realising much of her distress was down to her husband’s infidelity, he noted that she had a mental disorder.
His analysis of the late princess was said to have been shared by other members of the royal family’s household medical team.
In a letter unearthed by the Mail on Sunday, dated February 1983, psychotherapist Dr Alan McGlashan, who died 14 years later, details how he was bought in after Diana separated herself from the royals.
Dr McGlashan, 84, wrote that he and his colleagues were “plainly scared” by Diana’s symptoms and “overawed by the possibilities of dynastic disaster”.
He said that Diana revealed that she had been given anti-depressants and ordered to take behavioural therapy — but nothing cured her.
She even admitted that she couldn’t shake a reoccurring dream that she had of giant sea monsters.
The concerns for the princess were raised in the months that followed Prince William’s birth in 1982.
Diana was just 21 at the time.
She was also battling raging bulimia, and was feeling depressed, uncertain and upset over much of her new royal life.
However, she was a master at turning on the charm in public and making others feel welcome and comfortable.
Other medical professionals waded in to diagnose the Princess of Wales’ problems.
The letter, also suggests that Prince Charles was deeply worried about his wife’s behavioral issues, even though he was painted as uncaring in Andrew Morton’s memoir “Diana: Her true story.”
And, it was the Prince of Wales mentor, a South African writer, Laurens Van Der Post, who recommended that she saw someone outside of the bubble of the royal family – like Dr McGlashan.
In all, Diana met the psychotherapist eight times, twice a week, at Kensington Palace. But soon cut contact.
Dr McGlashan concluded there was no medical issue and no danger of any heriditary condition.
He concluded: “She is a normal girl whose troubles were emotional, not pathological.
“She is a very unhappy girl, facing situations on various fronts which she finds difficult to deal with, though making a courageous effort to do so.
“She has been surrounded by an army of doctors… and has been dosed with anti-depressants & sleeping drugs, and Behaviourist techniques.”
He adds: “Her doctors had been treating her as a patient with an obscure and dangerous illness which baffled them.
“Her symptoms plainly scared them. She complained to me that they all treated her ‘as if I were made of porcelain’.
“It was a difficult and delicate situation for me, coming into such an overloaded medical scene, but this was greatly simplified by D [Diana] herself, who has gently but firmly distanced herself from them all, having made what I think is a very good contact with me.”