'She altered irrevocably what it means to be royal'
Princess's legacy is the warmth felt by the British public for her two sons
'Goodbye England's rose, may you ever grow in our hearts,' sang Elton John at her funeral. Diana dead? The shock of it arrived in waves. Wave upon wave of disbelief.
The Princess of Wales was the most famous woman in the world, dazzling with the incandescence that fame bestows on its most graceful exponents. The idea that all that radiance, that intense young life had been snuffed out in a few cruel seconds in some scuzzy Paris underpass. No. Sorry. Category error.
Twenty years on, how is the Diana legend holding up? Well, there is no doubt that she changed the royal family, and changed it for good. Diana altered irrevocably what it means to be royal.
In July, Princes William and Harry produced a TV tribute that made it plain they see themselves as their mother's champions. Harry's memory of being on the other side of a room and feeling the force of her love for him was the finest tribute any mother could wish for. "She set us up well for life," William said, by which he meant her insistence that the brothers did normal kids' things outside the palace walls.
The princes have been criticised for speaking out about mental health, but it's a very Diana thing to do. What she did by holding the hand of a man with Aids, William and Harry may yet do to lift the taboo around depression. The brothers made public the anxiety and self-doubt that gnawed away at their mother in private.
This novice princess was taking on a daunting role. The British royals in the past had inspired awe, fear and respect; none had made the people feel protective.
Diana once said the royal family thought that her marriage to Charles fell apart because of her bulimia, when it was the other way around: the unhappy marriage caused the illness. It's not a mistake her emotionally intelligent sons are likely to make.
Witness the way the princes make a beeline for a baby in a crowd. Harry, in particular, is a magnet for small people. He looks happiest in the situations that make normal members of the royal family feel most uncomfortable.
The ability to inspire affection in people can be hereditary. It has not gone unnoticed that more and more requests pour in for visits by William and Kate, and Harry.
The Faustian pact between Diana and the media - the only weapon available to her, perhaps, but ultimately fatal - has left a lasting impression on her children.
"William literally believes that the media killed his mother," says a friend. This accounts for his obsessive protectiveness of the Duchess of Cambridge and their children. "One of the reasons the bond with Kate is unbreakable is because she was the first person he talked to about his mother's death."
The same is said to be true of Harry and Meghan Markle. The princes will do anything to avoid the chaos of their own childhood which, ironically, has made the future of the monarchy in Britain more stable and secure.
Can it really be two decades since the phone rang on my bedside table, dragging me up from a deep well of sleep? The story that was supposed to last my whole life (Diana and I were just a few months apart in age) had ended in the most brutal manner. All those chapters still unwritten. The loss felt deeply personal, and still does.
At Balmoral, the Prince of Wales was in anguish, weighing up whether to let William and Harry sleep until morning, granting them a few more innocent hours in which their mother was not dead.
Diana's death was a Rubicon for the monarchy. It was forced to confront just how out of touch it had become. By strictly observing protocol, the queen and the Palace were perceived to be showing the princess the same lack of compassion in death that they had dealt her in life.
The 'top lady', as Diana called her, was obliged to leave Balmoral and return to London, where she made a live broadcast to the nation - an extremely rare occurrence. Protocol be Princess Margaret was distressed by the smell of rotting bouquets outside her Kensington Palace apartment.
"She said the hysteria was rather like Diana herself," recalled a lady-in-waiting. "It was as if everyone got to be as hysterical as she was when she died."
But Margaret's cut-glass condescension was on the way out.
Diana may have tested the royal system to its limits, but she was no republican. "I so want the monarchy to survive," she wrote to her butler Paul Burrell, "and realise the changes that [sic] will take to put 'the show' on a new and healthy track".
Since the Princess of Wales's untimely death, the queen loses no time in turning up to support victims of national tragedies. When she chatted in a Manchester hospital to a little girl injured by the bomb at the Ariana Grande concert, you could imagine Diana smiling her encouragement.
At her funeral in the Abbey, all those years ago, the princess's favourite hymn, 'I Vow to Thee, My Country', co-existed with Elton John playing piano. It shouldn't have worked, but somehow it was wonderful. Diana proved that it was possible to be royal and modern.
In so doing, she guaranteed the survival of an institution that caused her so much pain. For that she will never be forgotten. The candle burned out long before the legend ever did.