Sarah Sands: Diana

Imagine how the scene at Sandhurst on Friday might have looked. The Queen, Prince Charles, Camilla and Prince William's girlfriend Kate Middleton arrive to watch the proud future king's passing-out parade. Five minutes before the music strikes up, a top of the range sports car swerves into the car park. Out gets Diana Al Fayed, glamorous, heavily Botoxed, dressed like Sharon Stone. With her is her slightly jowly husband Dodi, wearing dark shades, and two small children, a boy and the girl that Diana always said that she longed for. Both are dressed expensively from Harrods children's department and are carrying the latest mobile phones and iPods. Diana murmurs something uncharitable about Camilla's hat.

The death of Diana, Princess of Wales is one of the great What Ifs of our times. One reason that Lord Stevens dismissed the theory that she had been murdered was that the last evening of her life was so erratically planned. At almost every point, a different course could have been taken.

The catastrophe lay in the random detail. At 7pm on Saturday 30 August, 1997, Dodi Al Fayed and Diana left the Ritz hotel in Paris to go to his apartment in rue Arsène Houssaye. They had planned to dine at a restaurant but changed their minds and returned to the Ritz.

Henri Paul, who had been drinking, was fatefully recalled to duty to drive them back again to the apartment. Dodi spoke to his father Mohamed al-Fayed, perhaps or perhaps not to inform him that he intended to propose to Diana once he got her home. At 12.20am on Sunday 31 August, the Princess of Wales, Dodi Al Fayed and their bodyguard Trevor Rees-Jones left the hotel at the back, while Dodi's chauffeur-driven car and back-up vehicle left from the front, acting as a decoy.

The What Ifs abound. This was not conspiracy but chaos. Diana's friend Lucia Flecha de Lima told the Stevens inquiry: "When I saw those last photographs of Princess Diana at the Ritz I did not see a happy person. It was my guess that she was already fed up with the situation."

One can imagine Dodi's excitability and self-importance and desperate desire to impress as he bustled Diana from one location to the next, mobile clamped to his ear as his father issued instructions. Their affair had lasted a month and already he was preparing to propose to her. According to Mohamed al-Fayed, a house in Malibu was being done up and the Duke and Duchess of Windsor's Paris villa was being viewed.

Laughably, Mohamed al-Fayed also claims that he told his son not to rush into anything. Yet Diana had already been inundated with gifts - bracelets, watches and a ring. It was truly a holiday romance. The couple had already had three, using all the Fayed paraphernalia of helicopters and yachts and staff. According to Mr Fayed there were more holidays in the offing. Once Diana had settled her sons back into boarding school, she was being lined up for Hong Kong and Tahiti.

Mr Fayed also claims that Diana appreciated the warmth and attractiveness of the Fayeds after the coldness of the British royals. He poses the question - with a presumption that makes you gasp - "If Dodi and Diana had wed, and if they had had children, Britain would have had, in effect, an alternative royal family. The attractive, personable Fayeds. Or the charmless German Windsors?"

It is highly improbable that Diana would have stuck with Dodi. I agree with Lucia Flecha de Lima that her body language as he places a hand on the small of her back to guide her out of the Ritz's revolving door screams: "Get me out of here." The Mediterranean manners of which the Fayeds boast could make you long for some Teutonic reserve. But it is not impossible.

The Fayed camp point out that Diana was a high-maintenance woman and was gravitating towards being a Have Yachts member of society. Like Elizabeth Hurley, she liked the conspicuous wealth of the international jet set, rather than the stinginess of the British upper classes.

Even her interest in charity was of the global Bono variety rather than unfashionable British royal causes, such as the British Legion. Dodi dabbled in areas of interest to her. He was a film producer and had friends in fashion. He could have bankrolled all her projects. Diana might have wiped the floor with Angelina Jolie. Of course she could have preferred the discreet virtue of the surgeon Hasnat Khan but, in some ways, Dodi might have suited her better. Would Khan, for instance, have agreed to commandeer a helicopter at a moment's notice because of Diana's whim to visit a fortune teller? Dodi did it without question.

One only has to listen to the ravings of Mohamed al-Fayed about Prince Philip ordering the murder of Diana to think that the Princess of Wales's short association with the Fayed family was a moment of madness. Yet the source of some of Fayed's wildest theories was Diana herself. She wrote to her butler Paul Burrell: "This particular phase of my life is the most dangerous - my husband is planning 'an accident' in my car, brake failure and serious head injury in order to make the path clear for him to marry."

The finale of insanity was that Diana meant Tiggy Legge-Bourke, her son's nanny, rather than Camilla Parker Bowles, when she referred to Charles's intended wife. This explains the bizarre scene in 1995 in which Diana confronted Tiggy at a Christmas party with the words: "So sorry to hear about the baby."

Mohamed al-Fayed claims that Diana egged him on in his abuse of Camilla Parker Bowles (and he has an impressive repertoire of expletives and foul insults). She was gleeful when he nicknamed Camilla "the crocodile" and roared with laughter when he trumped that with "Dracula".

Diana, Princess of Wales was unstable and self-dramatising. Mohamed al-Fayed was not merely bad luck, he was her nemesis. Yet, that is not all she was. She was caught in a freeze frame of her life. But part of her appeal was her chameleon qualities. She was both shallow and deep-feeling. She was both vengeful and forgiving. She fell in and out with people. At the time of her holiday in the south of France, she had argued with her brother, Earl Spencer, after he refused her a retreat at Althorp, because he did not want a media circus, and she was not speaking to her mother Frances Shand Kydd.

According to Paul Burrell, Diana had a telephone conversation with her mother in May 1997 in which they rowed over Hasnat Khan. Mrs Shand Kydd had allegedly made a derogatory remark about Muslim men and Diana slammed down the phone. Because of her death, the feuds became final. Mohamed al-Fayed was able to proclaim that Diana was cast out by her own family and by the royals. It was the Fayeds who provided sanctuary.

It is an unavoidable consequence of untimely death that you have not made your peace with those around you. There is plenty of contrary evidence that Diana had left behind her Panorama phase during which she wanted to bring the Palace down. Paul Burrell writes in his book A Royal Duty that she would have defended the Windsors against Earl Spencer's reproachful funeral eulogy in which e said: "We, your blood family, will do all we can" to protect her sons from the constraints of their royal existence.

Burrell writes: "No one could have been more devoid of hatred than the princess and no one wanted to see the House of Windsor survive more than she. Had [Earl Spencer] known his sister, he would have known the truth."

The contradictions and confusion of Diana's death were also present in her life. Who could claim to know her absolutely? There have been testaments from almost all her circle but all of these are partial and true of the moment rather than eternally. More than other women, Diana, Princess of Wales, was many-sided.

Even while she was enjoying being pampered by the Fayeds, she spoke three times on the telephone on the final day of her life to Susie Kassem, a retired magistrate and hospital visitor whom the princess met at the Royal Brompton.

Diana did not have a "set" of friends but a disparate group of confidantes from very different walks of life. She was warm-hearted but capricious. As Paul Johnson, one of her unlikely mentors, said of her: "She would say what good advice, how right you are, and then go and do the opposite."

Lord Stevens may have tried to produce a clear portrait of her state of mind, but it was always going to end up as a Jackson Pollock. Every attempt to categorise Diana, Princess of Wales, is unsatisfactory. Most of all, the title bestowed on her by Alastair Campbell "The People's Princess". She shared Mohamed al-Fayed's slight disdain for the "German" Royal Family, indeed she used the term before he did. She came from purer aristocratic stock. She was brought up in Althorp, one of the nicest country houses in England, was one of the few suitable virgin Sloanes on offer and was great friends with the Royal Family. There is nothing of "the people" in Diana's background.

What made Diana so mesmerising was her altering states. The Queen, in contrast, is magnificently dull. She is the same as she always was, her hair the same, her interests the same. Diana's moods and desires changed wildly. She altered her hair style as often as her clothes. Her one constancy was her fierce love for her children.

This is my final heresy about Diana? It has been a tragedy for her sons to lose their mother. But it has allowed the greater influence of their father, during their crucial years. Diana was emotionally unfettered. She would speak of her great joy sitting in bed with her sons, eating ice cream and watching movies. Would the boys have become weak and spoilt if they had continued closeted in this maternal world? The movie The Queen is funny and poignant about the royal response to Diana's death. Prince Philip's answer was to take the princes stag-hunting. The royal way of life looks isolated and barmy from the Alastair Campbell/ al-Fayed point of view but it has a sense to it.

The institution of monarchy is not rational and it survives on tradition. The royals were true to themselves to dig in at Balmoral when England threatened to change. They have been proved right. Princes William and Harry announced this week a concert to mark 10 years since their mother's death. They showed their mother's charm, but they were visibly, indisputably, Windsors, just as Zara Phillips is a Windsor. Diana's blood family, and al-Fayed's alternative royal family, would not have saved the boys; they would have imperilled the monarchy.