In the centre of the scrum Manuel Rivas-Taquias, whose uncle was murdered and whose mother was imprisoned by the Pinochet regime, had the radio pushed to his ear. Suddenly he gave a huge smile and the crowd erupted.
It was a fair bet that the former dictator, behind the walls of the private hospital where he has been treated for the past few weeks, heard the noise.
"There will be celebrations around the world tonight," said Gloria Smith, another Chilean protester.
In part, she was right. From Santiago in Chile to Madrid's Plaza del Sol, opponents of the former dictator celebrated Britain's decision to uphold what they considered was natural justice.
In Spain, Isabel Allende, daughter of the democratic Chilean president ousted by General Pinochet in 1973, said it had been a "marvellous" decision. Around her the crowds scornfully chanted "Happy Birthday, General!" (He was 83 yesterday.)
In France, MPs applauded, and the Prime Minister, Lionel Jospin, said: "This is a surprise, a joy, bad news for dictators." The Swiss said they would be continuing their request for General Pinochet's extradition.
In Chile itself there was a celebration at the Santiago-based headquarters of the Association of Families of the Disappeared. Women hugged and wept as they released thousands of white balloons to commemorate the victims. One of the group's leaders, Viviana Diaz, said: "We feel our missing family members in our hearts. We believe justice has started for them. Today was an important step, a triumph for human rights. It tells heads of state they can not kill or torture."
But celebration was not the only story. With a passion equal to that of his opponents, supporters of General Pinochet, including Baroness Thatcher, said Britain was wrong. "The senator is old, frail and sick, and on compassionate grounds alone should be allowed to return to Chile," she said.
In Santiago the British and Spanish embassies stepped up security against crowds of Pinochetistas, who attacked journalists outside the Pinochet Foundation.
They also threatened to march on the villa used by the British ambassador, Glynne Evans, in Las Condes district, although she and her staff are believed to have moved to a safer location.
General Pinochet's son, also called Augusto, said the decision was a "cruel and sadistic blow that goes beyond the rights of Mankind".
The Chilean President, Eduardo Frei, was expected to announce he would press the government's case to set free General Pinochet for humanitarian reasons and to prevent further polarisation and disturbances.
But behind both the celebrations and voices of protest, there was little doubting the importance of the decision by the law lords. Whatever one's views on the rights or wrongs of the decision, observers agreed that the implications were dramatic. In effect, the weasel words about diplomatic immunity for heads of state have been overturned by Britain's highest court, overruling what a group of almost equally senior bewigged figures decided less than a month ago.
Spain is not the only country wishing to bring him to trial. The Swedish Prime Minister, Goran Persson, has said he should stand trial. A Belgian judge said suits filed by Chilean-born Belgians were admissible.
Switzerland asked for extradition in connection with the disappearance of a Swiss-Chilean student in 1977. Italian magistrates have opened an investigation into General Pinochet over alleged complicity in murder.
If the news is bad for the general, the implications for others who have committed political crimes are even worse. The law lords' decision is not a technical precedent for anywhere except the United Kingdom. None the less, the applause on all sides of the French parliament yesterday when the news was announced is a reminder of the cultural sea-change in recent years, traceable back to the end of the Cold War.
In the old days, superpowers backed their respective tyrants, a view reflected in the US phrase, with reference to a Latin American dictator: "He's a son of a bitch - but at least he's our son of a bitch."
Now, some might argue, morality provides its own justification for taking action. The fledgling International Criminal Court, whose creation was half-blocked by the United States this year, is intended to make it possible to prosecute those who have committed crimes against humanity anywhere in the world.
While the Home Secretary, Jack Straw, could reject the extradition request from the Spanish judge Baltasar Garzon, for the moment the Chilean democrats and their supporters are celebrating.
In the words of Sheila Cassidy - stripped, tortured and held in solitary confinement in 1975 - "It's a great moment for England and for Chile. I feel proud to be English today."
Additional reporting by Liz Nash in Madrid and Phil Davison, Latin America Correspondent.Reuse content