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.
More top news
Further bursts of rain with blustery winds
Conquering what is thought to be the world's biggest wave surfed was "scary" and like being "chased by bulls", a British surfer has said.
The former national security adviser is to be the first White House official sentenced in Robert Mueller’s investigation.