How many people were in the car which crashed killing Lady Di?

Most people past their mid-20's can remember where they were when they heard about Lady Di being killed in a car crash in 1997. This has a parallel with the JFK assassination, where it became a cliche to ask where their parents or grandparents were when they heard of his death.

However, when it comes to the Mandela Effect there's also a spooky parallel.

There's a well-known one surrounding the number of people in the car when JFK was assassinated, and now there's one concerning the number of people in Lady Di's car when she died. Some remember it to be 5, when all reports today show there were 4. The confusion comes from them remembering 2 survivors, not 1, and not being able to name who survived apart from Trevor Rees-Jones.

Conspiracy

There are many conspiracy theories round the death of Lady Di, but the idea there were 5 people in the car is a relatively new one. The main one is that it wasn't an accident and someone wanted her killed, and Dodi's father, Mohamed al-Fayed, spent millions of pounds investigating this. The police spent years investigating it under Operation Paget, which examined 175 different theories about what happened that night.

Stories range from Diana being pregnant to the infamous note she left earlier:

I am sitting here at my desk today in October, longing for someone to hug me and encourage me to keep strong and hold my head high. This particular phase in my life is the most dangerous. [...] is planning 'an accident' in my car, brake failure and serious head injury in order to make the path clear for Charles to marry.

Diana's bodyguard had already died in a car crash which she believed was not an accident.

It's known that the CCTV cameras in the tunnel were all mysteriously turned off or facing the wrong way at the time of her accident, and so the eyewitnesses describing a white Fiat Uno could not be corroborated by evidence, but is that also true of the number of people in the car?