We can only speculate about how that milestone might have been marked or even what the Royal Family would look like today had Diana not tragically died in 1997 – how would she view Charles’ marriage to Camilla? What would her relationship with Meghan be like? Would she have been able to prevent Harry’s split with the rest of the family? – but the fact remains that 24 years after her death, the People’s Princess remains a fascinating figure to millions across the globe.

Most fascinating of all is her death itself. The events leading up to the tragedy, as well as just what caused the speeding car in which she was traveling to fatally lose control and smash into pillar 13 of the Pont de l’Alma tunnel in Paris, remain the subject of fierce debate, conjecture, and conspiracy theories.

In 2019, I conducted a new investigation into her death for my book Diana: Case Solved. Along with a team comprising a former detective, a paparazzo who was in the pack of snappers trailing her every move, journalists, crash scene investigators, forensic experts, and automotive engineers, we pored over every tiny scrap of evidence in a bid to find out what really happened that fateful night.

We investigated the myriad conspiracy theories – that a chasing paparazzi pack had caused the car to lose control, that she was eliminated by shady international arms dealers, that MI6 killed her after learning she was pregnant with Dodi Fayed’s child, even that Charles had ordered the hit…and ultimately the evidence led us to one inescapable conclusion.

Diana was not killed by international arms dealers, or the secret service, or, in fact, by anyone deliberately. Her death was not the direct fault of the paparazzi either. It was, rather, the end result of a tragic sequence of events nobody could have foreseen, or perhaps even prevented.

My team and I not only proved this – we found the evidence that confirms it.

We also found evidence of another scandal, another conspiracy, entirely… and, most extraordinarily, how a crucial figure in Diana’s death was actually ordered by French police to keep quiet.

So how did all the myriad Diana conspiracy theories start? And why do they continue to hold traction over 20 years later? The answer lies in two, apparently, separate, but crucially important, facets of the case.

The first is the sheer incompetence of the French authorities in the immediate aftermath of the crash. The area was not properly sealed off, the scene became contaminated, people were allowed to come and go almost at will, and vital evidence was lost, mislaid, or destroyed – all fuel for those looking to stoke the fires of conspiracy.

In the days and weeks that followed, and perhaps in part due to a kind of panic as the attention of the world focused on the French investigators, things went from bad to grotesque. Witnesses were ignored, or their statements lost or discounted. We spoke to one American couple whose important eye-witness testimony was taken vi