The country's most famous bastion of free speech and lawful free assembly has become the home of fundamentalists who are prepared to use violence to silence their opponents. One of the speakers there last Sunday, a white British convert to Islam said: "I do not believe that absolute freedom of speech is a good thing. The West doesn't really believe in that freedom either. No one is free to say exactly what they want."
The Royal Parks Constabulary has increased the number of officers on patrol and mounted police now join the crowds that gather round the Sunday soapboxes. Fighting erupted between rival religious sects a few weeks ago, when an Iraqi Muslim speaker was arrested for stabbing a Lebanese Christian.
The Iraqi was a well-known figure at Speakers' Corner for his military uniform, Iraqi flag and praise for Saddam Hussein, Hizbollah and Hamas. When Lebanese Christians protested to the police about his inflammatory speeches, riots began. Four police officers were injured as they tried to clear hundreds of people from the area. The gates to Speakers' Corner were then locked, an event unheard of in its 124 years as a symbol of free speech.
Tensions between London's array of Arab and Muslim groups have been growing for months and police have been receiving complaints about intimidation by Islamic fundamentalists at Speakers' Corner.
Speakers' Corner began in 1855 when 150,000 people gathered in this north- east corner of the park to demonstrate against a Sunday Trading Bill. There was no legal right of assembly there and only after several more demonstrations - notably by supporters of the Reform League in 1866 - was freedom of speech in the park established in 1872. Anyone who wishes may speak on any subject as long as they avoid obscenity, blasphemy or any incitement to a breach of the peace.
Speakers' Corner was still thriving in the 1960s as a mass rallying point for anti-Vietnam and anti-nuclear causes. In 1987 Tony Benn stepped on to a soapbox to read extracts from the banned Spycatcher, telling a 500- strong crowd that "the time has come when those who believe in freedom, democracy and justice must make a stand".
Today, one lone old socialist remains among the fundamentalists on his decrepit paint-chipped stand, mocked by passing tourists as he continues to call his comrades to arms.
Now, instead of the once traditional concerns of Speakers' Corner - political theory, justice and the state of democracy, alongside more esoteric matters such as the fluoridation of the water supply and extra-terrestrial sightings - the sound and the fury is with religion.
Cy Banda, a South African Christian, has been assaulted five times; recently he brought a private prosecution against a Muslim who attacked him. He says that Speakers' Corner changed dramatically in 1987 after Salman Rushdie's Satanic Verses was published, but now the tension is more acute than ever. "The Muslims don't like their beliefs challenged in a public forum. These guys don't like democracy yet they use a democratic forum to speak."
Last Sunday, Muslim speakers, clutching the Koran and surrounded by tightly- knit packs of Muslim men, railed against the wicked West and the media that distort the truth of Allah. Next door the Christian speakers, evangelical and born-again, preached their own messages of doom and damnation while their banner-carrying admirers shouted "Praise the Lord!" and "All have sinned!".
The traditional debating format of speech-making followed by challenge and response has almost completely gone. Hecklers stay away from the religious speakers, focusing their attentions on softer targets. The few who dare to challenge the fundamentalist speakers make sure to stay well back from the crowd. Fourteen police officers circulate, carefully watching for the first sign of trouble.
An oasis of calm, undeterred by the new ferocity all around him, Lord Soper, the 93-year-old Methodist preacher, arrives mid-afternoon and is helped up on to the stand.
He has been coming to Speakers' Corner since 1925. Frail but eloquent, he looks around him and talks on the futility of violence.
He once described Speakers' Corner as being a "fellowship of disagreement" but today he is concerned about the violent turn those disagreements take.
"There is a cultivation of violence that has increased," he says. "I understand that violence and I will not dismiss it as an evil thing. It is a cry for help."
He was himself attacked when, during the war, he came here to preach pacifism.
A regular at Speakers' Corner since the 1960s, Dr Simeon Ivanov, a Bulgarian, looks around him and sighs. He mourns the days when Speakers' Corner was a place for serious discussion. "Decay, decay, decay," he says. "Most of the speakers now are religious, which is not in the tradition of Speakers' Corner. It was always a place for political discussion more than religious fundamentalism."