Dr Khan told how they began dating in September 1995 after the Princess accompanied him  to see his aunt and uncle in Stratford-upon-Avon. “Diana and I had a very good relationship with no personal problems. The only problem we did have was with the media and the only place we could have any real privacy was at Kensington Palace,”  he said.

“We had a normal sexual relationship and I have no reason to think that Diana was ever unfaithful to me.”

Dr Khan said he later learnt that Diana had asked Burrell to talk to a priest about the feasibility of them getting married in secret.

“I thought it was a ridiculous idea,” he said. “She just said everything would be all right. That was her answer to everything – it will turn out all right.”

He added: “A lot of people have said to me that even a married man would leave his wife if he had the chance of being with Diana, but I did not want that sort of lifestyle.”

He told how he and Diana were still embroiled in a passionate romance when the Princess accepted Mr Al Fayed’s invitation to join his family with her sons on a holiday at his villa in St Tropez in July 1997.

It was on that holiday, between July 11 and 20, that Diana and Dodi fell for each other.

Just over a week after she returned, she ended her relationship with Dr Khan, the court heard. “When Diana went to St Tropez with Mr Al Fayed, everything was fine between us,” the surgeon said.

But while she was away he felt there was something wrong and his suspicions were confirmed when they met in London and he confronted her.

“When we did meet up in Battersea Park she was not her normal self and she kept looking at her mobile phone,” he said.

“I told her that I thought that she had met somebody else and it must be someone from Mohamed Al Fayed’s contingent. I had no idea who it could be.”

They met the next day at Kensington Palace. “It was at this second meeting that Diana told me that it was all over between us,” he said.

“She denied there was anyone else involved. I strongly suspected there was someone else and I remember saying to her, ‘You are dead’, meaning her reputation was dead.

“I said this because I was sure that it was someone from Mohamed Al Fayed’s group and that was how I felt about anyone involved with him.”

He only learned the truth about Diana’s romance with Dodi when he heard it reported on the radio.

Dr Khan also said Diana was concerned about her safety and feared her car had been tampered with. But he insisted she was not paranoid.

He described how in December 1995 she said she had changed her car from an Audi to a BMW after her brakes were tampered with.

Dr Khan also revealed she had told him that her love rival Camilla had suffered “two accidents” and that Prince Charles had arranged for his future second wife to have better security. The hearing continues.