The heart surgeon Princess Diana fell passionately in love with has moved to Pakistan where he has been pictured for the first time in years.
Dr Hasnat Khan was dubbed 'Mr Wonderful' by Diana who was besotted by the gentle and brilliant doctor.
He was said to have been the only man she ever truly loved.
The princess had a doomed two-year romance with the Pakistan-born surgeon who became her secret 'soulmate' after meeting him at the Royal Brompton Hospital in London.
They split up just weeks before her death in Paris in August 1997.
Now it has been announced that Dr Khan has relocated back to the country of his birth to run a heart hospital there.
He is the Dean of the Jinnah Institute of Cardiology in the city of Lahore.
Dr Khan always shunned the limelight and, in recent years, he worked tirelessly as a consultant cardiothoracic surgeon at Basildon and Thurrock University Hospitals in Essex, living with his second wife and their young daughter.
Seen for the first time in years, Dr Hasnat Khan (pictured) - the only man Princess Diana ever truly loved - was photographed in Pakistan where he has relocated from Essex to run a heart hospital
Dr Khan pictured this week in Pakistan meeting the chief minister of Punjab, Maryam Nawaz, as he takes up his new post running a heart hospital in the city of Lahore
Dr Hasnat Khan in London in 1997 around the time when he was the secret soulmate of a besotted Princess Diana
It is thought he will continue to return to the UK to carry out consultancy there while setting up a new base in Pakistan. The hospital says he is still employed there and hasn't moved to Pakistan full time yet.
Dr Khan was photographed meeting Punjab's chief minister Maryam Nawaz on Thursday, 'who welcomed his decision to leave England and serve his home country', it was reported.
He was seen wearing a smart suit and striped yellow tie as he was congratulated by the chief minister who said: 'It is heartening that a son of the soil has chosen to serve his underprivileged compatriots.'
The new hospital is being set up to become one of the country's centres for heart treatment with ambitious plans being put in place to transform the region into 'a global hub for medical tourism'.
Dr Khan previously built a heart unit near Jhelum, the city in Pakistan where he was born, and he has always spent part of each year treating poor local people without charge.
Born in 1958, he completed his early medical training before moving to Britain where he built a distinguished career as a cardiologist at the Royal Brompton Hospital, a specialist centre for heart and lung diseases.
He trained under the world famous transplant surgeon Sir Magdi Yacoub.
In 1995, Princess Diana was visiting a friend having treatment there when she struck up a friendship with Dr Khan.
Described by friends as a shy and intensely private man, Dr Khan was aged single and just two years older than Diana when they met.
'One day I came out of the hospital and she was going in and she shouted at me, 'Oi, where are you going?,' Dr Khan recalled a few years ago, when the Daily Mail secured a rare interview with him.
'I said I was going to my uncle's house in Stratford-upon-Avon to collect some books and I blurted out, 'Do you want to come?' She said yes and that was it really.
'We drove up there, drove back and found this wonderful connection. She was very ordinary in many ways, a normal person with great warmth.'
He split from the princess (pictured, in her infamous interview with Martin Bashir for television programme Panorama) just weeks before her death in Paris in August 1997
The couple enjoyed unlikely dates at the Breakspear Arms, a pub not far from the Harefield Hospital in Middlesex where he had also been working.
Diana is also said to have smuggled the burly doctor into her Kensington Palace residence hidden in the boot of a car.
Much as he liked Diana - who was still married to Prince Charles at the time, although firmly separated - in the end, Dr Khan could not bear the thought of living his life in the glare of publicity as partner to the world's most famous woman.
The Princess's closest friends previously spoke of her distress when the surgeon ended their relationship.
She had met Dr Khan's family in a February 1996 visit to Pakistan, a trip on which she wore a traditional shalwar kameez - baggy trousers paired with a flowing dress.
While there, Diana visited a cancer hospital run by former test cricketer Imran Khan, a distant cousin of Hasnat's, and is said to have made a significant effort to win over the rest of his family, including his grandmother, with whom she'd had a long-standing correspondence.
The couple were said to have discussed marriage and having children together, the possibility of moving to Pakistan, and Diana even introduced him to her sons.
She is also said to have been so smitten at one point that she considered converting to Islam so the pair could marry.
Describing how the relationship ended, Dr Khan once said: 'I knew I would not be able to live a normal life and if we ever had children together, I would not be able to take them anywhere or do normal things with them.'
Even after their break-up, she remained in contact with Dr Khan's family.
Dr Khan said: 'There are a hundred could-have-beens.
'She could be living very happily and married and having more kids, with me or with someone else. It could have led in that direction. I try not to think about these things. I can't change anything now.'
Diana went off with Dodi Fayed - believed by some to be an act of recklessness designed to cause Dr Khan jealousy - which proved a fateful choice, with the princess and Dodi dying together in the car crash in the Alma tunnel in Paris on August 31, 1997.
Dr Hasnat Khan as depicted in the Netflix drama series The Crown
Dr Khan, who attended Diana's funeral ceremony at Westminster Abbey in September 1997, once said of her legacy: 'She did a lot of work. She got to where she was on what she was.
'She didn't just shake hands and wave at people. She actually did things. Now she has gone, there is a huge vacuum - she has left a gap.'
While never speaking of their relationship while the princess was alive, Dr Khan was furious when a big budget movie which claimed to reveal the true story of their romance and have his approval was released in 2013.
Dr Khan - who has also featured in the hit Netflix series The Crown - said of the movie called Diana which starred Naomi Watts and Naveen Andrews: 'You could tell from that picture that it is all just presumed about how we would behave with each other, and they have got it completely wrong.
'There wasn't any hierarchy in our relationship. She wasn't a princess and I wasn't a doctor.'
After Diana's death, Dr Khan continued to devote his life to his work, living quietly for many years in east London.
A decade after Diana's death, Dr Khan married Hadia Sher Ali, a Pakistani descendant from Afghan royalty, who was 29 at the time. However, their arranged marriage ended after just 18 months.
In 2017, the Daily Mail revealed he had found love again after getting engaged to Somi Sohail.
The couple were photographed together at a charity ball in London's Mayfair.
The event was organised to raise money for Chain of Hope which works towards its long-term goal that all children, wherever they are born, have access to quality cardiac care in their own countries.
It was said that, of all the men caught in the vortex of Diana's life, none ever acted with more dignity and discretion than Dr Khan.
He always ignored the grotesque speculation about her death and rejected the financial rewards that he could so easily have made from writing about their love affair.
In 2017, the Daily Mail revealed he had found love again after getting engaged to Somi Sohail. The couple were photographed together (pictured) at a charity ball in London's Mayfair
When the Mail interviewed him in 2021, Dr Khan remained the same gentle, unassuming figure that Diana fell in love with, dedicated to his work here in Britain which he said he regarded as home.
But now it seems he has expanded his horizons, with an ambitious new role in Pakistan.
One thing will never change - his devotion to his patients.