LEADING ARTICLE: The Queen of Hearts turns up trumps

The Queen would never have done what the Princess of Wales did this week. She must have been appalled at her daughter-in-law's indiscretion, her flagrant breaching of royal protocol. There was Diana, on a platform with a Labour politician, letting everyone know how badly she felt about homelessness. She spoke emotionally about "sixteen- and seventeen-year olds who resort to begging, or worse, prostitution, to get money in order to eat. Young people whose physical and mental health has been severely damaged by life on the streets."

This is not the discreet, diplomatic, Windsor way of doing things. The closest the Queen has ever got to telling us how she feels about anything was when she reached for a Latin textbook. "Annus horribilis" is hardly language to stir the hearts of the nation. Diana would not use it: she would probably think it was a form of colonic irrigation gone wrong.

The Princess of Wales is different from her in-laws. She "really cares" and she is not going to stay quiet. Her latest intervention had Tory backbenchers jumping up and down as though she had wrapped herself in the red flag, joined Tony Blair's front-bench team and was on the stump for Labour. She had "been duped by a socialist speech writer," fumed Harry Greenway, a Conservative MP.

It is easy to understand his fears. The princess shared a platform with Jack Straw, Labour's home affairs spokesman. She is clearly exploring new possibilities for her role in British life. Diana is an exciting and unpredictable figure, unwilling to be fettered by Buckingham Palace precedent and practice. More nervous Tory MPs, nursing tiny majorities, can perhaps be forgiven for believing, in their wilder moments, that she could even become party political, an unguided missile fired into the general election campaign.

But it is ridiculous to think that the Queen of Hearts is Labour's trump card. Her speech was free of party favouritism. This was Diana having her say on a social issue about which she feels passionately, at a conference organised by a charity, Centrepoint, of which she is patron.

The problem that the Princess of Wales poses to the Establishment does not concern politics. She is well aware of the requirement that members of the Royal Family should stay above party politics. She knows that her position would become untenable if she broke with that tradition. Her challenge, rather, is about style. She is unwilling to go along with a tight-lipped, reserved, buttoned-up, elitist image of monarchy that is utterly removed from the way people live their everyday lives.

In a nutshell, the Princess of Wales is coming to represent an alternative vision of the modern monarchy. If the latter was re-created in her image, it would still be charismatic and awesome, but it would also be much more in touch with the concerns and realities of most people's lives. She speaks to and on behalf of modern young women. Her trips to the gym, her talk about the difficulties of being the right type of parent, her confessions about bulimia and her speeches on a host of social problems from homelessness to Aids, strike a powerful chord with the rest of society.

The Queen and her children traditionally steer clear of this difficult territory. The Prince of Wales has his own public causes. He has vented his spleen on the brutalism of some modern architecture, standards of spoken English, and on environmental issues. But he does not have his wife's common touch. He will always remain a rather isolated and remote figure, a product of another, fast-disappearing age.

As for the Queen, she prides herself on a detached monarchical style. She has an almost Pavlovian aversion to appearing partisan. Not even Pierre Brassard, the disc jockey who masqueraded as the Canadian premier, could trick her into abandoning her studied diplomatic persona.

The neutral, neutered character offered by the monarchy is a long-standing element in the British constitution. It has served the present queen well, particularly during the Eighties when the prime minister, Margaret Thatcher, was a divisive force in British life. But her studied distance from day-to-day issues leaves the Royal Family peculiarly out of touch: the monarchy's habits, ways and image are increasingly obsolescent, belonging more to the Fifties than the Nineties.

Princess Diana takes more risks. She speaks about emotions. She is exploring the limits. She is breaking fresh ground. That's dangerous: if she gets the national mood wrong, she risks alienating the public. But her style also offers an opportunity to reinvigorate an institution which has become dangerously out of touch with a people who, after all, pay the bills.

The events of the past couple of days resemble similar attacks on the Church of England in the Eighties, when it became a vocal critic of poverty. The thundering Establishment said that the church had no place in politics and should stay quiet. But the bishops kept up their barbed comments, won friends beyond the ordinary faithful and, as a result, gave themselves a little more relevance.

Likewise, the Princess of Wales will probably annoy many people with her outspokenness. Her motivation may be questioned: it seems to be a combination of revenge against her husband, an obsession with self-publicity and a genuine to desire to do good. But, whatever her aims, she could, in the process of tackling controversial issues, free the Royal Family from its emotional strait-jacket and rescue it from its growing isolation. That would be a service to us all.

The Princess of Wales will almost certainly never be Queen. But at the very minimum she could give Charles - and her son - a model for a more open style of monarchy, at once more risky and more relevant to modern times.