In his book Unnatural Causes published in The Mail on Sunday, Shepherd states the princess “actually suffered just a few broken bones and a small chest injury – but this included a tiny tear in a vein in one of her lungs".
"Her specific injury is so rare that in my entire career I don’t believe I’ve seen another," explains the doctor, whose 30 year career has seen him examine evidence from 9/11 terrorist attacks and the 7/7 London bombings.
In a 2017 documentary to mark the 20th anniversary of Diana's death, her sons Prince William and Prince Harry blamed the death of their mother on the paparazzi who chased her into the Paris tunnel.
Harry admitted one of the "hardest things to come to terms with" was that those who chased her into the tunnel continued to take photos of her while she was injured in the back of the car.
“She’d had quite a severe head injury but she was very much still alive on the back seat,” the 34-year-old explained in the BBC documentary.
“And those people that caused the accident, instead of helping, were taking photographs of her dying on the back seat.”