Hundreds of people have joined a rally to denounce Britain's air strikes in Syria against Islamic State.
The Stop The War protesters, who gathered at BBC Broadcasting House in London and planned to march to Downing Street, took particular aim at the 66 Labour MPs who crossed the floor to secure the green light for action.
The Socialist Party supplied an open microphone for the event, with over a dozen speakers lining up to voice their anger under the watchful eyes of police.
One speaker, who gave his name as Tony, labelled Prime Minister David Cameron as "insane" and "evil" for pursuing a more aggressive approach.
He said: "You can't bomb your way to peace."
Helen Pattinson, 24, who is part of a group that has been campaigning at schools, questioned the funding for military action.
She said: "How come they can find money to drop bombs on other countries to create refugees... but they can't find money for health, for education, and for young people to have a decent future?"
Nancy Taaffe, from the Socialist Party, told the crowd: "We've been here before people, haven't we?
"When we're told about peace and reconstruction, and then... we see the bodies coming back, we see the bombs in Baghdad market and the sectarian civil war erupted when they kicked the hornets' nest of the Iraq war."
She added: "We say no to the continued violence, we say no to the terror and we say no to the racism that is the fallout of this war."
Ms Taaffe called on Labour politicians to bring a motion back to parliament to cease the air strikes.
She said: "We will back you up with a mass peace movement from outside."
Ursala Khan, 22, of Birmingham, said she was at the rally to show support for innocent Syrians who could be caught up in the strikes.
She said: "If I was in that situation - if I was in Syria - I would hope someone on the other side of the world would stand up for me."
Ms Khan said she does not believe assurances that no civilians will be impacted.
She said: "There is always going to be collateral damage, people will always be killed."
Ms Khan said there are other ways of tackling IS, such as finding out who they sell weapons to and who is buying oil from them.
She said: "I think (David Cameron) probably just wanted an easy option and probably just wanted to make more money. Typical Cameron."
The protest closed streets as it weaved along Regent Street, past Piccadilly Circus and Trafalgar Square. The crowd chanted: "Stop bombing Syria, no more war" and "They say warfare, we say welfare".
Outside Downing Street, deputy leader of the Green Party Dr Shahrar Ali attacked Prime Minister David Cameron for his pledge to accept 20,000 Syrian refugees over five years.
He said there were more than 4.2 million in Syria: "What is the UK's commitment judged against that? 0.005%."
He added: "Refugees are not welcome here, according to Cameron. Refugees are welcome here according to us."
Protester Arij Limam, 21, said the vote to extend air strikes had shown MPs were prepared to ignore their constituencies.
She said: "They've just shown that they don't care what the British people think, they're supposed to represent us and they didn't - they went against what all of these people want, which is peace."
Ms Limam added: "They just voted to escalate the war, and it's not going to solve anything - they're carrying on because I think they want the spoils of war, they want what comes after this."
She added: "I think that's a ridiculous reason to start war and to bomb innocent people."
Ms Limam's Tunisian parents were kicked out of the country for opposing the government of the day, but managed to return after 20 years.
She said: "When I saw that the same things was happening in Syria, it was an amazing feeling.
"I realised these people in Syria, they did want to stand up against their government as well.
"They just wanted to do what we did in Tunisia. Their outcome was unfortunately not so good. It's been five years now and (Bashar) Assad's been killing his own people for five years.
"I feel like Assad is the problem, and we're not addressing that."
Nahella Ashraf, chairman of the Greater Manchester Stop The War group, said more than 70% of the British public was against air strikes and believed they were unlikely to stop Isis.
She said: "If anything, it's just going to create more anger towards the West.
"We've seen the history of Iraq, Afghanistan and what happened in Libya - we haven't made the world a safer place."
Ms Ashraf said while the Tory Government was the main culprit, it was also unacceptable for so many other MPs to vote against the wishes of the public.
She said: "I know they say they voted with their conscience, but actually they work for us.
"In a democracy, they're meant to listen to their constituents, and what's clear is that they're so far removed from how people in the street feel."
She added: "As long as they keep bombing, we're going to keep marching and showing how angry we are."