Police put on a “show of strength” against Extinction Rebellion on Tuesday, arresting at least 90 protesters as officers contained a demonstration to Parliament Square.
Around 3,000 activists descended on Westminster on Tuesday morning where they formed a blockade - beating drums and waving flags - in front of traffic around parliament.
It was hoped the event would cause the maximum disruption possible on the first day MPs were due back in the House of Commons after the summer recess.
However, the first day of a planned fortnight of action was met with a wave of arrests as activists ignored the conditions placed on the protest by Scotland Yard under Section 14 of the Public Order Act.
The force had ordered crowds to remain within Parliament Square Garden, but began to remove protesters by force when thousands instead flooded the surrounding road.
By the afternoon, police had formed a line blocking activists on either side of the square, arresting anyone who refused to move.
The Metropolitan Police said 90 people had been arrested as of 6pm for offences including assaulting an emergency worker, obstructing police and public order breaches.
It comes after police faced criticism over their light-touch approach to Black Lives Matter protests in the summer, prompting Priti Patel to call for tougher tactics.
The Home Secretary was said to have had a "firm" conversation with the chief constable of Avon and Somerset Police in June after the force failed to stop a statue of Edward Colston, the slave trader, being torn down and thrown into the River Avon by protesters in Bristol.
On Tuesday, Paul Stephens, a Scotland Yard officer turned climate activist, said the force had taken a harder line with Extinction Rebellion than at similar events in October last year.
Mr Stephens, who retired two years ago after 34 years with the Metropolitan Police and now acts as a liaison for Extinction Rebellion, told the Telegraph: “In October they had a Section 14 on the second or third day, based on the disruption they could see, but this one was based on disruption they perceived was going to happen.
“We don’t agree with that really, Parliament Square is made for lobbying MPs and protests.”
He claimed Extinction Rebellion had requested the use of the whole square for the protest to assist with social distancing, but received no response despite four meetings with police.
“You’ve seen the number of police that have been used, our genuine motive for liaising with the police beforehand is to cut down on the number of police they need,” Mr Stephens said.
“I think it’s a show of strength and it’s about power and control really, which is a bit sad.”
Among those taken away by police was John Lynes, a 92-year-old campaigner who has previously been involved in Extinction Rebellion events, according to the campaign group.
Walking with a stick, he was escorted patiently out of the square by a group of police officers just before 5pm.
A spokesman for the group said that Extinction Rebellion was planning to further defy police orders to disperse by 7pm and instead continue blocking the road.
Campaigners from the group have planned “two weeks of civil disobedience” across the UK to put pressure on politicians to take drastic action against climate change.
A doctor who worked on the frontline of the pandemic at the NHS Nightingale hospital in London was one of dozens of health workers supporting the first day's demonstration.
Chris Newman, a GP in north London, said he and many colleagues were now more concerned about climate change than Covid-19.
He told the Telegraph: “I’m fully aware of the suffering and human cost of coronavirus, it’s not something we’re taking lightly.
“The concern would be that there is always a short-term problem and when you are dealing with a huge long-term issue that is getting ever closer - then when do you tackle it?”
He added: “Even in the middle of a pandemic, we are more concerned about climate change than the pandemic. We’ve seen how bad this is, but we’re even more worried about climate change.”
Dr Newman said he had been given confidence that socially distanced protests would not risk an outbreak in Covid-19 cases after research saw no significant spike after this year’s Black Lives Matter protests.
Last year, more than 1,700 arrests were made during Extinction Rebellion's 10-day "Autumn Uprising", which saw major disruption across the UK.