British Prime Minister Theresa May's office suspended Foreign Office Minister Mark Field on Friday while an investigation takes place into his treatment of a climate change protester at a gala dinner. The City of London Police, the Cabinet Office and the governing Conservative Party are all looking into the incident that took place Thursday night at the Mansion House dinner, an annual black-tie event that showcases the financial industry.

May's office said she saw the footage and found it "concerning." Treasury chief Philip Hammond was speaking when activists, wearing red dresses and sashes reading "Climate Change Emergency," began milling around tables at the event.

Video shows the female protester, Janet Barker, walking forward toward Hammond when Field blocks her path. He then pushes her into a pillar to turn her around and places his hand firmly on her neck as he leads her away.

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"I was simply trying to walk past his chair, yeah, so they were really over the top," Barker told BBC News. "… I'd quite like him to go on anger management perhaps, and I hope he doesn't do it again."

She said she wouldn't press charges. Field apologized and said he deeply regretted the incident.

U.K. Foreign Office Minister Mark Field forcibly removes Greenpeace protester Janet Barker during the gala Mansion House dinner in London June 20, 2019, in an image taken from video. APTN

"In the confusion, many guests understandably felt threatened and when one protester rushed past me towards the top table I instinctively reacted," he told ITV. "There was no security present and I was for a split-second genuinely worried she might have been armed."

The demonstration comes after another group of climate change activists disrupted life and travel in the British capital in April, bringing parts of London to a standstill as they demanded net carbon emissions be reduced to zero by 2025. Field, a lawmaker whose constituency is in central London, had complained to London authorities at the time that commuters in London were "quite rightly fed up" with the travel disruptions caused by protests from the Extinction Rebellion group.

In a letter to Police Commissioner Cressida Dick, Field said while he respected the right to peaceful protest, shutting down traffic had gone beyond "a good-natured exercise in free speech" and become detrimental to locals. Hammond continued his speech at Mansion House after a brief pause, and defended the government record on climate change.

But the protest laid bare other issues. It comes at a moment of feverish political activity in Britain, fueled by the ongoing divisions resulting from the 2016 Brexit referendum to leave the European Union.

Several lawmakers have been threatened. Adding to the pressure is the contest underway to determine who will lead the Conservative Party. The vote will also choose the country's new prime minister — the leader who will determine whether the country leaves the E.U. in an orderly fashion, crashes out in economic chaos or remains in limbo. One of the candidates in that contest, Foreign Secretary Jeremy Hunt, also happens to be Field's boss.

"Mark has issued a full and unreserved apology," Hunt told BBC News. "He recognizes that what happened was an overreaction, but what we need now — in his interests but also in the interests of the lady involved — is a proper independent inquiry by the Cabinet Office. That's what going to happen."

Experts in policing, such as Peter Williams of the Liverpool John Moores University, expressed alarm that security surrounding some of Britain's most high-profile leaders should be so lax — particularly at a time tensions are so high. Had the demonstrator been carrying a weapon rather than a sheaf of papers, the incident might have gone differently.

"This could have been a grievous event," Williams said. "This could have wiped half of the government out."

But as the video became public, other public officials debated the question of whether force should have been used at all, given that peaceful protest is a hallmark of democracy. London mayor Sadiq Khan, who belongs to the opposition Labour Party, described the footage as "truly shocking."

"Violence against women is endemic in our society and this behavior is unacceptable," he said. Conservative and former soldier Johnny Mercer countered: "Honestly? Try being in our shoes in the current environment. He panicked, he's not trained in restraint and arrest ... calm down, move on, and be thankful this wasn't worse."