A largely peaceful demonstration against global capitalism flared into violence yesterday when anarchist protesters attacked a McDonald's restaurant and fought a running battle with riot police during clashes across the centre of London.
In echoes of the riot that caused havoc in the City last June, demonstrators selected the international burger chain, apparently as a token of their contempt for capitalism.
The attack, in which furniture was wrecked and windows smashed, marked the start of sporadic clashes that marred an otherwise peaceful day of protests by about 5,000 people who marched through London, congregating in Parliament Square, where they planted flowers and dug an impromptu "pond".
Police conducting one of the biggest security operations seen in the capital for decades tried to quell disturbances by throwing a cordon around Trafalgar Square.
But trouble continued into the evening as more than 1,000 protesters made their way along The Strand and Aldwych, smashing shop windows during a violent game of cat and mouse with heavily armoured riot police.
Two lines of mounted officers were used to charge the mob, pushing demonstrators across Waterloo Bridge and into a sealed-off area. Demonstrators also gathered in Kennington Park, south London, amid concerns that a planned celebration party could provoke further trouble.
But by 10pm most protesters had begun to disperse, leaving a rump of about 150 herded together outside Kennington police station. The majority were released after being searched and photographed by police. A total of 42 people were arrested during the violence.
A police officer was detained in hospital with facial injuries after being hit by a flying brick during the attack on McDonald's.
The worst violence of the day flared as demonstrators filed from Parliament Square into Trafalgar Square. A small group broke away along Whitehall, where they threw bricks and bottles at police lines and attacked the restaurant.
Jason Jarvis, 33, said: "A gang appeared out of nowhere and charged straight into the restaurant. Within seconds it looked like a bomb had gone off inside, with glass spraying out on to the street ... and people who were in the area ran away screaming."
Police in riot gear used vans to block off exits from the square, but most of the 14,500 officers on duty or on reserve were kept out of sight.
Earlier, protesters had defaced the statue of Winston Churchill in Parliament Square, daubing it in red paint and placing a "mohican haircut" of lawn on the wartime leader's head. The Cenotaph on Whitehall and Nelson's Column in Trafalgar Square were also attacked with anarchist symbols.
Tony Blair condemned the "mindless thuggery" of eco-activists who engaged in running battles with police. "The people responsible for the damage caused in London today are an absolute disgrace," he said last night. "Their actions have got nothing to do with convictions or beliefs and everything to do with mindless thuggery.
"To deface the Cenotaph and the statue of Winston Churchill is simply beneath contempt. It is only because of the bravery and courage of our war dead that these idiots can live in a free country at all."
Ken Livingstone, the candidate standing as an independent for the London mayoralty this week, who has been at pains in recent days to distance himself from "direct action" by protesters, issued a strong condemnation of the violence.
"I utterly condemn the violence and destruction of property by mindless thugs," he said. "I fully support the efforts of the police to put an end to the activity of these violent hooligans."
The clean-up operation in London got under way last night. Turf dug up from Parliament Square was removed, while the graffiti-daubed base of Churchill's statue was boarded up.
Elsewhere in Europe, the workers who are usually commemorated on May Day took a back seat to the far right as neo-Nazis rallied in German cities and nationalist parties held demonstrations in France.
More than 5,000 German anarchists erected barricades and threw stones and bottles at police last night as rioting erupted in the Berlin district of Kreuzberg. The crowd at one point tried to move towards the government district but were repulsed with water cannons.
On the previous night, 26 people had been injured in clashes between anti-capitalist protesters and police in the northern city of Hamburg.
In France about 3,000 members of the far-right National Front party marched to the Paris Opera House behind a woman on horseback dressed as Joan of Arc, whom the anti-immigration party has adopted as its patron saint.