Masked anti-establishment protesters are expected to gather in central London tonight in their thousands. Wearing Guy Fawkes masks from the film V for Vendetta, long associated with the internet activist collective Anonymous, the demonstrators will join millions of demonstrators in hundreds of cities around the world with a broad anti-capitalist agenda.

The protest attracted condemnation last year, after a large police presence turned scenes ugly. Both officers and protesters were injured, with several members of the public requiring first aid. Around 50 arrests were made, including three men aged 38, 55 and 50, on suspicion of being in possession of offensive weapons.

Almost 20,000 people have indicated on Facebook that they'll attend the annual march, which police claim was attended by 1,000 people last year, but which by other accounts attracted at least 10 times that.

Police have warned about "masked criminals seeking to run amok", and are prepared to make arrests if violence breaks out again.

However, the protest's organisers hit back, saying on their Facebook page that "the police are not your friends". They asked the Metropolitan Police "to restrain from violence and their usual mob mentality".

Metropolitan Police Commander BJ Harrington said: "As we look ahead to this weekend, my message is simple: if you want to protest peacefully, that is your right and we want to work with you.

"If you commit criminal acts – that is not peaceful protest – and you are liable to be arrested."

Police have used the Public Order Act to limit the demonstration to a three-hour march from Trafalgar Square to Whitehall, between 6pm and 9pm.

Chief Superintendent Pippa Mills said: "We will always facilitate peaceful protest and have a strong history of doing so. However we have strong reason to believe that peaceful protest is the last thing on the minds of many of the people who will come along this year.

Anonymous Mask
Anonymous masks will be worn by protesters iStock