After all the anger and the bitterness that had passed between them, there was a deep irony in the sombre journey to Paris of the Prince of Wales yesterday afternoon, to bring home the body of his divorced wife. In life, Diana had been a torment to the royal family, exposing the fustiness and flaws of the ancient institution. Her impulsive nature, warmth and, most importantly, her willingness to reach out to the real people in the street showed how out of touch the family firm had become. Retaliatory palace attacks on her judgment and stability tended to backfire.

But her death solves no problems for the monarchy. Far from it. There are those who say she was its hope of successful adaptation to the modern world and that the institution might not long survive her.

The arrival of Diana and, to a lesser extent, Sarah Ferguson, from the world outside, forced changes that cannot now be reversed. The royal family has creakingly and belatedly embarked on a sort of programme of modernisation. In response to Diana's high-profile crusades on heartrending issues, such as AIDS and land-mines, Prince Charles has begun to emerge from under a pile of architectural drawings and demonstrate his own humanity.

But her public appeal was phenomenal and the monarchy badly needed that popularity to rub off on her sensitive son William, whose task of becoming one day a successful modern king has at a tragic stroke become indescribably more difficult.

"She had reinvented royalty in recent years in perhaps the only direction it can go in and survive," said royal biographer Anthony Holden yesterday, "and her legacy will be her son William, who has already been through appalling stress and suffering as a result of his parents' divorce and will surely miss her benign influence."

William and Harry have not been closeted and isolated from the world in the way that their father and all princes before him were, and even more importantly, they have not been starved of affection in the name of tradition and protocol.

Diana, herself a child of a broken marriage, made much of her determination to be a good mother. Nobody has doubted her success. Against all royal precedent, she has been privately and publicly affectionate, and they have loved her deeply in return. "Diana lived for them and they worshipped her," said Mr Holden.

She had introduced them to real life, even in mundane ways, such as standing in a queue at a shop to pay for things they wanted to buy. Then there had been the trips to theme parks and the cinema, the white-water rafting and tennis which ordinary boys take for granted. She had also taken William on her visits to the homeless.

In the recent interview in Le Monde, she talked of how much it meant to her to get close to children and the sick on her charity trips. "I feel close to people, whoever they are. We are straightaway on the same level, on the same wavelength. That's why I upset those in some circles. Perhaps because I am a lot closer to people who are low down than to those who are up high, and the latter do not forgive me. Because I have a real relationship with the most humble. My father always taught me to treat anybody as an equal. I have always done that and I am sure the seed has taken root in William and Harry too."

Her disappearance from their lives is a disaster for the boys. "Do not underestimate the impact on them," warned a long-standing palace insider, "particularly William, who is very sensitive and now has this intolerable extra burden to bear."

There is every likelihood that the boys' upbringing will now conform to the traditional princely pattern, remote from ordinary life. "They love their father as well," said Mr Holden, "but those who wish to see the monarchy survive must be concerned about its future in the hands of custodians who are perhaps not adapted to the modern world."

In her interview on Panorama, Diana mentioned that she thought the monarchy should walk hand-in-hand with the people more than it does. "I think that is the only kind of monarchy that can survive in Blair's 21st-century Euro-Britain," said Mr Holden. "Maybe the prince will modernise more than he has so far. Let's hope so."

It is possible that the royal family will now close ranks against outsiders, pull up the drawbridge and hope the criticism will go away. Queen Elizabeth is expected to attract sympathy, but Prince Charles is far more exposed.

"The monarchy might be in danger," said social affairs commentator Polly Toynbee, speaking on BBC Radio 4. "There might be a sense of public indignation against Prince Charles. The poor man may find that where he goes he is not much liked and that he is blamed for the tragedy of Diana's life."

There is that concern at the palace too. "Some of the blame may go on being attached to the Prince of Wales because of his relationship with her and his final abandonment of her," said the source.

It also makes even more difficult the question of marriage to Camilla Parker-Bowles. In the eyes of the Church, nothing will have changed, since the relationship of Charles and Camilla was a factor in the break-up of the prince and princess's marriage, and because Camilla is still a divorcee. In the eyes of the public, as Diana passes into legend, the remarriage may now be intolerable.

Yesterday, as the family, from the queen to Prince Harry, bore its tragedy with the dignity for which it is famous, and Prince Charles flew home with the body of the woman he had rejected, there would have been room only for thoughts of sadness. But in days to come, the royal family must begin to wonder what the future has in store for the British monarchy.