“You don’t have to thump me!” shouted pro-Brexit supporter Hilary Roper-Newman at a female passerby outside the Houses of Parliament.

“She has just thumped me,” the 70-year-old West Yorkshire woman shouts to a policeman at the gates of Westminster, pointing at a woman in a multi-coloured anorak who has disappeared into the crowd.

The policeman offers to stand by in case the thumper comes back.

Roper-Newman, an author of children’s books, is grateful. She stays in position, holding her giant “We Voted Leave” placard.

“I’m here to fight for the people’s mandate which parliament are in breach of not acting upon. We want to leave. We voted to leave,” she tells The Irish Times.

She bristles at the suggestion of a potential risk of a no-deal Brexit to Ireland or the Irish Border.

“You have to stop using words like ‘crashing out’ and ‘risk’,” she said.

She, like most Brexiteers, believes the Border can remain open with “modern-day technology” for large companies and “special visas on cars so people can automatically cross”.

Ground zero

“The Northern Irish backstop has been a deliberate block for us to leave the EU,” she said.

On the footpaths outside parliament, there is regular close-quarters verbal sparring between pro- and anti-EU protesters.

Here in central London, “SW1” is ground zero for Britain’s nervous breakdown over Brexit, a divided people bicker outside a divided parliament.

The pro-Brexit crowd were pleased British prime minister Boris Johnson prorogued parliament on Monday night for five weeks.

Some hope he can block the new law blocking a no-deal exit and believe he will come back with a large majority “outside the M25” in Middle England if he can successfully call an election.

“Traitor MPs,” shouts pro-Brexit Jeff Wyatt (55), dressed as a medieval Crusader, over that law.

“What has become of our parliament? We have got 328 MPs openly rebelling against the British people,” the Milton Keynes businessman said.

“We have a traitor parliament,” he chants at a crowd.

“You use the language of ultra nationalism!” shouts a Remain supporter, decked in the blue and gold stars of the EU with flag in hand.

“We are winners, you are a loser. We won the f**king vote,” screams a Brexiteer back at him.

Hilary Roper-Newman, pro-Brexit protester at Westminster. Photograph: Simon Carswell

“You need to scrub on your maths, you anti-democrat,” roars another.

Inside, parliamentarians have speaker John Bercow to intervene when proceedings become heated. Outside, there are police; they mostly observe.

Monday’s House of Commons announcement from Bercow, a regular thorn in No 10’s side, that he will stand down as speaker next month predictably divided the crowd outside along pro- and anti-Brexit lines.

Political constipation

“What has happened in this institution behind me is akin to political constipation complete with a lot of wind – he has facilitated that,” said Londoner Kate Brown, a carer who wears an “Out of EU Now” badge.

Steve Bray, better known as the “Stop Brexit” guy who has protested outside Westminster every day parliament has sat for the last two years, says he is “quite sad” at Bercow’s departure.

“What people don’t like about him is he has followed parliamentary procedures which has inevitably helped the Remain side,” said Bray, whose voice is still strained from screaming through his loud-hailer.

The Welsh activist has his share of unparliamentary language thrown at him.

“F**k Europe! ” screams a man from the window as a white van speeds by.

Protesters on both sides appear shattered by the three-year trauma of Brexit.

“It has totally split the country. It is just a complete nightmare,” said Lorraine Chappell, a retired businesswoman wearing a “Make Britain Great Again” cap who wants out of the EU now.

Elke Day, a German woman living in England for 50 years, and her husband spent money travelling up from Kent to protest against Brexit instead of on “a new honeymoon” to celebrate their 50th wedding anniversary.

“To me, it is like a bad dream,” she said. “I just wish one morning I could wake up and it was all going to be like before June 2016.”