If people had actually known what was going on, it would have been perfectly obvious that Diana could have died at the hands of the paparazzi. But no one did know - no one seemed to want to know.
Only three months ago I went out with Mark Saunders, one of the handful of paparazzi who followed Diana every day, in an attempt to find out.He talked frankly in his car as he waited by Kensington Palace for the princess to emerge in hers. I sat in the passenger seat as he chased her, and I walked behind him when he moved furtively down the street to "hose her down" with his huge camera.
I hadn't cared that much about Diana before. After I spoke to Saunders - and read his book about stalking her - I felt so angry, appalled by what she was left to endure by the rest of the world. A phrase kept going through my head: "What fresh hell is this?"
But no one did know - and the hell was in the details. It wasn't a civilized business being at the end of those long lenses. Diana, a woman very often on her own, was constantly followed by a swarm of ruthless, hostile strangers.
They surrounded her car, jostled her in the street and insulted her to her face, even though she had paid for the shirts on their back. This was the other side of her life, the side no one, apart from her tormentors, saw.
It was the cumulative effect that made their presence torture - as she told them, again and again. It is hard to convey how unbearable this must have been. They were there every day, and they had been for 16 years. She probably spent more time with them than with her sons.
"Get lost," she would say whenever she saw them. "Why don't you leave me alone?" As she started to confront them, they took to running away, like dirty old men - after they had gotten her picture.
"It's become abusive and harassment," she said on the BBC-TV documentary Panorama. "It goes on and on and the story never changes."
It got so bad that she walked around, Saunders said, "constantly looking over her shoulder, her eyes darting this way and that." He had snapped her from rented apartments, from hotel rooms, from up trees, behind bushes, under cars. He went to extraordinary lengths.
Saunders had informers who would ring him if they spotted the princess. He followed her on foreign vacations, to restaurants, to shops, to clinics. There was almost no moment she could be sure she was alone.
It was a private war between them, and when I was there it was clearly becoming dangerous. At first Diana tried to deter them by putting her head down, or her hand or bag in front of her face. When that didn't work, she lectured them, ran from them, hid from them. Sometimes she would stay in Kensington Palace for a week at a time.
Eventually, she was reduced to weeping and pleading. They were unmoved. I don't think anything could have moved them. That was when she started to break down. I think the harassment sometimes threatened her sanity. But it was never going to end. Like a fatal disease, they would be with her until death.
Saunders' book, "Dicing With Di," has been withdrawn by Blake, its publishers. They should have kept it in the shops. People would have got some idea what she went through.
Once she was held at bay in a taxi. She hid her head. A photographer shouted at her: "Put your . . . head up and start acting like a . . . princess!"
She was also snapped by a paparazzo minutes after being told of the death of her father. She was in Lech, Austria. "No, no, no, no, no, no, no, no, not now!" she screamed and crumpled on to the balcony. Within 20 minutes every frame had been sold.
There was the time she took her sons to see the film "Jurassic Park" in London's Leicester Square. When Diana came out of the cinema she spotted two paparazzi, Glenn Harvey and Keith Butler. Harvey, who co-authored the book with Saunders, gives his account of what happened:
"A flash of black shot across my view. It was Diana, but this was a Diana I had never seen before. It was her face but it was now red and twisted. She was racing toward us through the crowds. Her eyes were fixed on us and then she let out a scream like a wild animal. The hundreds of milling pigeons took to the sky. The shocked tourists stopped walking and looked our way. William and Harry rushed up behind to see what the bellowing was. No monster's roar they'd heard in the film could have scared them as much a this one.
" `YOU MAKE MY LIFE HELL,' she screamed. `YOU MAKE MY LIFE HELL.'
"Shocked and shaken, Keith put his cameras down on the ground. Diana now seemed shocked and embarrassed at her explosion and, realizing the commotion she had caused in the square, turned away. Her hands covered her face as she strode toward the car. She brushed away beads of sweat from her brow, then ran the last few meters to the waiting car still crying with rage. William and Harry chased after her, now very concerned for their mother's welfare. The car sped off with Diana still holding her head in her hands, crying."
What I found so disturbing was that Saunders and the others didn't seem to connect her almost unhinged outbursts with their activities. They blamed Charles, or the Palace - anyone but themselves. They couldn't seem to think of her as a human being. In the adrenaline of the chase, she simply became prey to be hunted down.
Their attitude was a flippant cynicism. Their slang for pho-to-graph-ing Diana was to "hose her down," "whack her," "target her" or "blitz her." They coined a phrase for her anguished confrontations - "being looned."
Most frightening were the car chases. I discovered that Diana had become so desperate to shake off her ruthless retinue that she would drive dangerously fast to escape. (She knew their cars; she knew their names only too well.) Then they would do the same. These Hollywood-style car chases across London, with the paparazzi speeding through back streets in the dead of night, sometimes with their lights off, were a common feature of her life.
After the BBC interview, Saunders and Harvey followed her up the highway. "It took her about five seconds to realize she was being followed," Saunders recalled. "Diana knows my car well enough, and I could see her looking at me in the rearview mirror. She indicated left and pulled across to the middle lane, slowing down considerably and forcing me to pass. And then, in a moment of insanity which to this day neither Glenn nor I will ever understand, she increased her speed and lurched back into the fast lane, coming up directly behind me. We were traveling at 90 mph when I felt her bumper touch the rear of my car.
" `What the hell is she doing?' shouted Glenn. He gestured wildly at her: `Back off . . . back off.' But Diana made no attempt to slow down. The cars carried on, bumper to bumper on one of Europe's most dangerous roads. By now I was genuinely scared. I could see Diana's face in the rearview mirror. She looked possessed. She was driving with only one hand, with the other gesturing wildly at me. Her car remained just millimeters from mine. Putting our lives on the line, I increased my speed, thinking it was the only way to escape her. At about 120 mph I lost her and managed to slip into the middle lane. Diana sped past."
Such incidents were commonplace. That was what I found so frightening - more frightening even than the unbearable pressure of being stalked and photographed without respite (and this from a woman who was psychologically fragile).
"If this harassment continues," I concluded in May, "her story could no longer just end in tears. Someone could die, and it might not be a paparazzo."
Given what was happening, I think it was lucky she survived so long.