Pro-Brexit, left, and anti-Brexit, right, protesters debate their views outside parliament in London, Thursday Jan. 10, 2019. Prime Minister Theresa May's proposed Brexit deal seems widely disliked by both pro-European and pro-Brexit politicians, threatening the exit agreement and future relations with EU. (AP Photo/Alastair Grant)
Some protesters wrap themselves in the European Union flag and noisily interrupt politicians’ television appearances. Others yell “Nazi” and “traitor”. Britain’s MPs are split on how to handle Brexit but they agree that the atmosphere in public spaces - often populated with angry demonstrators - has become ugly and intimidatory.

This raucous brand of street activism has raised questions about where the boundaries of free speech now lie.

MPs this week called on police to tackle intimidation of politicians and journalists outside parliament after protesters yelled abuse at a prominent Conservative lawmaker.

More than two-and-a-half years since Britain voted by 52% to 48% to leave the EU, the country remains divided. Demonstrators who back Brexit and others who want to stay in the EU have become a fixture.

While protests have generally been peaceful, politicians and journalists say the atmosphere has turned nasty.

On Monday, Conservative MP Anna Soubry, a pro-European who has called for a second Brexit referendum, faced chants of “Soubry is a Nazi” and “liar”. The abuse continued as she walked back to parliament with cellphone footage on Twitter showing her surrounded by men, some in yellow vests similar to those worn by protesters in Paris, shouting “liar”, “fascist” and “scum”.

Sky News journalist Kay Burley has also faced abuse. She said demonstrators who disliked Soubry monitored TV channels so they could turn up and hurl abuse at her.

In a letter to the London police chief Cressida Dick, 60 MPs expressed concern about the “deteriorating public order”.

“An ugly element of individuals with strong far right and extreme right connections... have increasingly engaged in intimidatory and potentially criminal acts,” the MPs, both pro-EU and pro-Brexit and from all political parties, wrote.

Monday’s fracas was a symptom of a growing malaise in British politics, according to Rob Ford, professor of political science at the University of Manchester.

It followed street scuffles during Scotland’s 20154 independence referendum and activists draping a banner from a bridge during the Conservative Party’s conference in 2017 saying “Hang the Tories”.

“I think Brexit deepened it this trend towards intensifying distrust of politics, politicians and the media,” Ford said. “That distrust is now becoming a serious obstacle to addressing complex issues.”

Politicians on all sides of the Brexit debate had encouraged this kind of thinking, Ford said. “I fear the beast that they have unleashed has now turned on all of them.” Ian Lavery, the Labour Party chairperson, said Monday’s events outside parliament were an attempt to silence political debate.

“They were incarnations of a campaign of hatred brought from the darkest reaches of the internet to the doors of our democracy.”

Labour MP Stephen Doughty, who organised the letter, warned there could be a repeat of the murder of Labour MP Jo Cox, killed a week before the 2016 Brexit vote by a man obsessed with Nazis and extreme right-wing ideology. Last year, a man accused of being linked to a far-right group pleaded guilty to plotting to kill another female Labour MP who, like Cox, was targeted as she was perceived as supporting immigration.

Brexit Minister Stephen Barclay said Monday's “appalling scenes” outside parliament showed how divisive Brexit had become.

Tim Montgomerie, a prominent pro-Brexit Conservative activist, said on Twitter the abuse of Soubry was unacceptable, but “a parliamentarian who advocates overturning a referendum result she promised to respect should not be surprised at unleashing such ugliness”.

Abuse has been rife, with left-wing author and Labour supporter Owen Jones posting a video on Twitter of protesters shouting “traitor” at him outside parliament.

Pro-Brexit MPs have also been targeted. In September, Conservative MP Jacob Rees-Mogg, a prominent Brexit campaigner, was confronted outside his home by activists who told his children “lots of people hate your daddy”. Reuters