Organisers of a huge protest against the Government's public spending cuts hailed the demonstration a "fantastic success" after hundreds of thousands of people joined the biggest event of its kind for over 20 years.
Between 400,000 and 500,000 teachers, nurses, firefighters, council and NHS workers, other public sector employees, students, pensioners and campaign groups from across the UK marched through central London to a rally where union officials and Labour leader Ed Miliband condemned the "brutal" cuts in jobs and services.
Violence flared away from the rally when a group of hundreds of activists, not connected with the union protest, clashed with police. They set off fireworks, threw paint and attacked shops in Oxford Street, Regent Street and Piccadilly.
Topshop and HSBC had their windows smashed, while paint and glass bottles were thrown at a Royal Bank of Scotland branch. Covering their faces with scarves, they fought with police and disrupted traffic, throwing lightbulbs filled with ammonia at officers and lighting a fire. Nine arrests were made and some police officers were injured.
TUC general secretary Brendan Barber said he "bitterly regretted" the violence, adding that he hoped it would not detract from the massive anti-cuts protest.
He told the Press Association: "I don't think the activities of a few hundred people should take the focus away from the hundreds of thousands of people who have sent a powerful message to the Government today. Ministers should now seriously reconsider their whole strategy after today's demonstration. This has been Middle Britain speaking."
Mr Miliband, who did not take part in the march, told protesters at the mass rally in Hyde Park that he was proud to stand with them, adding that the Government was wrong to make such deep cuts in public services. He was heckled by a small number of protesters when he said that "some cuts" were needed, but most people applauded his speech.
"The Tories said I shouldn't come to speak here today but I am proud to stand with you. People are here from all walks of life and different backgrounds, speaking for mainstream Britain. Our struggle is to fight to preserve, protect and defend the best of the services we cherish because they represent the best of the country we love."
A total of 214 arrests were made during the day for a variety of offences including: public order offences, criminal damage, aggravated trespass and violent disorder, with people in custody at various London police stations, the Metropolitan Police later said.
The Met Police later said at least 31 police officers were injured during the protests. The injuries were described as "relatively minor", including cuts and bruises, suspected whiplash and a possible broken collar bone.