Diana - Seven days that moved the world: People power never before seen in quiet cosy Britain

"It's people power. In the Philippines, Marcos was deposed. Now, this will be a watershed. There's no possibility that Charles will become king. Everything has changed."

You do not expect to hear such angry words from respectable former royalists. But there were many nods of agreement in the queue outside St James's Palace yesterday, as John Dawkins, a retired travel agent from Richmond, delivered his tirade.

You can mock,but the reality is that the emotions in the queue snaking back and forth, waiting to sign the book of condolence, are quite unlike anything that Britain has ever seen before. Yesterday, the queue was longer than ever: thousands waited for twelve hours through the night. It seems to be the power of devotion. But this is devotion to Diana, not to the Royal Family. One clear message that emerges: Buckingham Palace, beware.

Some were worried that the press had blackmailed the Royal Family into publicly showing their emotions. But everyone knew that she had been frozen out by the Palace. The dogged, good-natured devotion on show at St James's and at Kensington Palace was a kind of revenge. In the words of one note, pinned to a barrier: "You alone are bigger than the whole Windsors. On Saturday when we lay you in your final resting place, we will be burying the Windsors, not you."

I have seen extraordinary crowds before. It was a privilege to experience the mood in the quiet but determined crowds in eastern Europe, as the Communist regimes collapsed, in quick succession. Jangling keys, ringing bells, and candles in the wind - the emotions were raw. All of us knew that these national acts of defiance were the precursor of revolutionary change. Now, astonishingly, there are hints of the same mood, in quiet, cosy Britain. It still seems difficult to comprehend.

The huge crowds that have come to queue outside St James's Palace and to lay flowers at Kensington Place are not revolutionaries. But they have chosen to demonstrate their grief in a way which they know will irk what Diana used to call "the Firm". The snub to the royal Diana-haters is conscious

For Buckingham Palace, the worst news is that the most radical revolutions often begin obliquely. The huge demonstrations on Tiananmen Square that challenged China's Communist regime in 1989 began as a mere mark of respect for the former Communis Party leader Hu Yaobang, who had recently died. He was part of the ruling apparat. But he was also - as everybody knew, just as they knew with Diana - at odds with that apparat. Homage to him was the most oblique kind of challenge to the regime itself.

In the Soviet Union, one important early sign that Russia had finally started to turn rebellious was at the funeral of Andrei Sakharov, Russia's greatest champion of human rights. For decades, ordinary Russians had not been interested in Sakharov's philosophy. Now, at his funeral, the change of tack was clear.

There were hypocritical tributes from those who had done most to destroy him, including from the head of the KGB. More to the point was the loyalty now shown by his fellow Russians. "Forgive us," said the slogans. The emotional outpouring over the death of Sakharov was a poignant sign that the break-up of the Communist system itself was on its way.

The point about these mass events is that nothing can ever be the same again. In Poland, millions came out on the streets for the first visit to his home land by the newly-chosen Pope John Paul II. Communist authorities pretended to be pleased. But they knew that this was not just a demonstration of Catholicism.

Many of those who went out on the streets to greet the Pope were not even believers. Instead, the mass demonstration served as a concealed way of demonstrating how great was the dissatisfaction with the regime.

Within a year, the strikes in Gdansk led to the creation of a free trade union, which itself paved the way for the final collapse of the old regimes across the region. This week's outpouring of grief, emotion and defiance in this country can never be repeated on this scale. Not for the death of the Queen Mother (strictly for the royalists; a kind of irrelevance), nor for the Queen (dignified but distant), and least of all for King Charles III, as he may become.

Charles's spin-doctors will try desperately to tell us that he is a deeply caring and lovable human being. In one sense, they may be right. It is easy to imagine him tossing and turning, sleepless because of the cares of the world.

But the public cannot be blamed if they now seek a human face to the monarchy, in a way that they did not before. To blame the public for its change in taste - as Buckingham Palace implicitly tries to do - is perverse. As Bertolt Brecht once retorted to Communist apparatchiks who complained about popular restlessness: "Dissolve the people, and elect a new one."

The monarchy is answerable to the people, and not vice-versa. Never before has this been so clear. Diana was the outcast of the Royal Family, because she was too human. The public wants the rest of the royals to show the same "humannness and courage to be yourself", in the words of one scribbled note at Kensington Palace. If they fail to do so, is the implication, they will themselves be cast out. The royals can be taken back to the shop and cashed in, at any time: full satisfaction or your money back, is the constitutional deal. The royals occupy Buckingham Palace only on sufferance - an obvious truth which some, perhaps including the Queen, have only begun fully to understand this week.

In the hours after Diana's death, one royal observer argued that this was "the most convenient royal death for 400 years". That may well be how it seemed at first to the cloistered royals themselves. The main troublemaker was gone. There would be no more Panorama interviews. Royal life could return to normal, according to Buckingham Palace rules.

But, as the crowds repeatedly showed in eastern Europe and elsewhere, once important changes of mood have taken place, there is no return to the status quo. In a sense, everything that has happened in the last 30 years can be seen as a slow-motion version of what Ryszard Kapuscinski, a famous chronicler of people's power, has described as the "zig-zag to the precipice". In the case of totalitarian regimes, this takes the form of a zig-zag between liberalism (which loosens people's fear) and repression (which makes them angrier than they were before).

The end-point is the same: the collapse of the regime. In democratic Britain, the zig-zag has been between aloofness and accessibility. "We are human - look at us," the Queen proclaimed, in effect, in the propaganda television film (ground-breaking, as it seemed at the time) Royal Family, 30 years ago. Later, the message came: "But not that human. How dare you pry?" Later still, the Prince of Wales himself was ready to go on television to bare his soul and tell us about his affairs and his tortured childhood. Only one message remained constant: "We are the Royal Family. And we expect you to respect that."

Quaintly, Communists in eastern Europe made last-ditch attempts to appoint a reformist leader when their fortresses were under assault - in order to prove to the people that everything had now changed. In all cases, they failed.

The royals may succeed better than the Communists did, in re-inventing their own image in order to survive. But, after this week, there is no question that their position is more precarious than it has ever been. The events of this week make it clear that, if William is to become king, many more changes - in other words, royal retreats - are yet to come.