Footage has emerged of an Insulate Britain protester being pushed by a Range Rover driven by a woman taking her son to school.

In the video a woman drives up to a roadblock protest at a busy junction, leaps from the black four-wheel-drive vehicle, snatches a banner and shouts at two activists: “I’m not joking, my son needs to get to school. Move out the way. Move out the way now.”

When the protesters refuse to move she gets back into her car and inches it forwards on to them. One screams as she is squeezed under the front bumper. Onlookers goad the driver on, shouting: “That’s it, that’s it: push them. Go on, push them.”

The Guardian spoke to the activist minutes after the incident, which took place last Wednesday during the group’s protest on the A1090 in Thurrock, Essex. “We were sat here and she drove up very fast and she got out to shout at us to move,” she said, her words punctuated by car horns. “We didn’t move and she accelerated. We kind of got trapped under the front of her car and were being pushed forward.”

When asked if she was hurt, she said: “I think so, but I feel quite a lot of adrenaline pumping.”

The video was shared by Insulate Britain. A spokesperson for the group said this was the first time it had published any footage of the violent reactions its roadblocks had provoked. She said supportive responses to the clip, which has been viewed 1.7m times on Twitter, had galvanised activists.

Insulate Britain is midway through a 10-day pause in its campaign of disruptive protests on critical roads in and around London. The group, an offshoot of Extinction Rebellion, has vowed to continue protesting “until the government gets on with the job of insulating Britain’s homes” or until its members are all jailed.

The group had hoped that between 50 and 100 members would be “climate prisoners” in UK jails by the beginning of the Cop26 climate summit in Glasgow beginning at the end of the month. But none have been held on remand for more than a week, with police complaining it has been difficult to bring serious charges.

In an effort to amplify the legal response, the government has taken out injunctions banning Insulate Britain from protesting on sections of the critical road network around the capital, which protesters have repeatedly breached. If convicted of contempt of court for defying the orders, the activists could face up to two years in prison.

On Tuesday at a return hearing at the high court in London for four injunctions, a judge indicated it could still be weeks before any Insulate Britain protesters go on trial. Mr Justice Lavender said it would not be him who presides over any trial, so he could not set a date with certainty. But he added: “I would hope that we would be back in court by the end of November.”

The next Insulate Britain protest is expected on Monday.