Ten people have been arrested as thousands of anti-capitalist activists took to the streets of central London to protest against political oppression.
Demonstrators wearing Guy Fawkes masks and carrying banners and placards descended on Trafalgar Square before marching towards Parliament Square at 6.30pm.
The Metropolitan Police said that as of around midnight 10 people were detained, including three on suspicion of assaulting police officers, one of a firework offence, three for public order crimes and one of attempted GBH.
A Met statement said: "Whilst the majority of those taking part were peaceful, there were pockets of violence shown towards officers; with fireworks and traffic furniture including barriers thrown at them.
Chief Superintendent Pippa Mills, the police spokesman for the event, added: “Police officers worked under challenging conditions. Despite numerous attempts, the organisers refused to engage with us ahead of the evening’s events.
“Our policing operation and work with our partners ensured that on the whole the event passed off without major incident.”
Protesters chanted anti-establishment slogans as they milled around, and some who had climbed on to the base of Nelson’s Column let off fireworks.
There was a heavy police presence at both Trafalgar Square and Parliament Square, as well as along Whitehall, with officers carrying riot gear, but the protest began peacefully.
There was a chorus of boos and whistles as a police officer warned protesters about their behaviour over a loud hailer.
The protest, the so-called Million Masks March, was organised by activist group Anonymous.
Steve Foster, a 36-year-old storeman from Liverpool, came to the capital to attend the event and make his voice heard.
He said: “The inquiry into institutional paedophilia is probably the main reason (why I am here). I am actually a victim myself, though not institutionally, when I was a kid.
“I want to see a real inquiry and I want to see prosecutions and people jailed in the establishment, where we all know it is rife. That is my biggest reason.”
Asked about the nature of the protest, he said: “I think everyone wants it to go peacefully really, just a peaceful demonstration.
“More and more people have been turning up every year so hopefully it will keep growing and growing until there will be change. There is one solution, revolution.”
Scotland Yard had earlier warned Anonymous it had powers to remove face coverings ahead of the march.
A statement on the Anonymous website said the group would have “bigger banners, louder voices, more people and a louder system”.
In a statement, the Metropolitan Police said they had attempted to contact organisers of the event “without success”.
And it added they had imposed Section 60AA of the Criminal Justice and Public Order Act 1994 across Westminster between 5pm yesterday and the early hours of this morning, which provides powers to remove masks when police fear a crime will be committed.
Scotland Yard said: “The Met Police deals with around 4,500 protests and events every year. These can range from a single protester to hundreds of thousands of people walking through the capital’s streets.
“Officers work with organisers to ensure that people are able to carry out their right to peaceful protest whilst ensuring Londoners can go about their daily business.”
Anonymous says it is protesting against austerity, infringement of rights and mass surveillance.
Last year’s Million Mask March saw a handful of protesters charged after hundreds descended on Buckingham Palace and Parliament Square.
Officers made 15 arrests during last year’s protest, which saw demonstrators clashing with police and a fire started near the palace, as well as damage to Nelson’s Column and the Victoria Memorial.
This year, some of the marchers again left Parliament Square to make their way to Buckingham Palace.
On the way they kicked and dragged over security railings and chanted “one solution, revolution”.
As they neared the palace they were met by a large police presence, and tried to drag railings away from officers at the Victoria Memorial.
Some missiles were thrown, including plastic cones and a road sign, at officers who had their batons drawn.
Police shouted at them to get back, and more officers came in to reinforce the line at the memorial.
The mood calmed, with many protesters sitting down in front of the police, before they moved off again.
Protesters also let off fireworks and threw firecrackers and missiles at police who were guarding the Victoria Memorial, hurling abuse at them.
Among the demonstrators were masked children as young as 14, who shouted that they were protesting against social services.
Comedian and actor Russell Brand was also spotted among protesters outside the Houses of Parliament, just as he was last year.
Nearby, a 66-year-old woman who gave her name as Maggie, from Plymouth, sat in her wheelchair in front of the parliament buildings clutching two posters protesting against the Government, her husband behind her.
She said: “I have come along basically to say to the Government, ’enough is enough’. They are corrupt, they are bringing in so many austerity cuts, the welfare reform hasn’t been thought out properly, yet Iain Duncan Smith seems to think it is working.
“I would hope that the difference (the protest will make) would be that the public who aren’t involved, those who are unaffected, might stop to think what is really going on.
“I hope that people strive for humanity, to be a bit kinder to one another, and not to believe all the lies.”
The rally was held to show anger at global corporations and government corruption, but protesters carried banners railing against everything from welfare cuts to fracking. Others handed out religious leaflets, and one woman was draped in a flag supporting CND, the campaign for nuclear disarmament.
After leaving Buckingham Palace hundreds of protesters made their way through central London, going to Piccadilly Circus, Regent Street and Oxford Circus, before marching to the BBC’s headquarters at Broadcasting House on nearby Portland Place and going along Oxford Street to Hyde Park and Park Lane.
The entire protest was filmed and streamed live online. Footage showed protesters pushing over bins, shouting at bemused shoppers and commuters and hitting cars and people with yellow flexible tubes.
In one section they surrounded a man driving a new Mercedes car and sprayed the back of it with an aerosol, pushing their tubes at him as he opened windows to remonstrate with them.