One Anonymous protester told of how he was moved to join the group after being arrested under the Computer Misuse Act, despite having "done nothing wrong".
Sean Roesner, 21, a self-employed computer programmer, travelled to tonight's protest with his brother and friend from King's Lynn, Norfolk this afternoon.
He said: "We turned up and the protest was at Buckingham Palace. When we arrived people were firing fireworks at the Palace.
"It was funny. I didn't have any but I would have fired some if I had.
"I joined Anonymous because I was arrested under the Computer Misuse Act. I spent eight months on police bail last year and had done nothing wrong."We are here to stand up for what we believe in, to make the world a better place."
Mr Roesner said his friend had been among a group of people encircled by the police on The Mall and was waiting for him to be released so they could return home.