The prime minister’s own sister Rachel branded his remarks “highly reprehensible” and said she did not recognise the person using the despatch box of the House of Commons as a “bully pulpit” as her brother.
And former prime minister Sir John Major accused him of “reckless and divisive behaviour” that was designed to incite opposition to the most important bulwarks of British freedom for the sake of his own re-election.
Mr Johnson sparked anger in the House of Commons on Wednesday by repeatedly using the words “surrender” and “sabotage” in relation to opponents of his Brexit plans, and accusing them of plotting to “betray the people”.
And there was fury when he dismissed as “humbug” a warning that he risked stirring up abuse of MPs. He also suggested that the best way to honour murdered MP Jo Cox – a Remain campaigner killed by a right-winger shouting “Britain first” – was to “get Brexit done”.
Ms Cox’s husband Brendan said the comments made him “a bit sick”. Labour MP Jess Phillips called an urgent debate in the Commons to denounce the PM’s “appalling” remarks and demand an apology.
Ms Phillips told the Commons that Mr Johnson – who sent junior minister Kevin Foster to answer questions in his place – was following a “tested and work-shopped” strategy to whip up hatred and division.
The Labour MP later revealed a man had been arrested at her Birmingham constituency office on Thursday afternoon after allegedly “smacking the windows” and shouting “fascist”. She said her staff had to be locked in the office during the incident, but are okay.
There was no apology over Mr Johnson’s language from Mr Foster or from the prime minister himself in a round of regional TV interviews on Thursday evening.
Mr Johnson acknowledged his language could be driving away the Labour votes he needs to get any Brexit deal through parliament, but rejected any suggestion that it was contributing to threats of violence against MPs.
Speaking to BBC North West Tonight on Thursday, Mr Johnson insisted: “It’s important to be able to use a simple English word like ‘surrender’ in a parliamentary context to describe a bill that gives the power to the rest of the EU to keep us locked in the EU by their own decision and to decide how long we should be there.
“I was sitting opposite people who were shouting all sorts of things at me all afternoon that were far, I’m afraid, harsher than that.
“And I don’t think I did say anything about a betrayal. What I worry about is if we don’t get Brexit done, then people will feel very badly let down. And that’s why we’ve got to bash on and get it done on 31 October.”
A senior government source also made clear that No 10 was ready to double down on its campaign to blame MPs for the failure to deliver Brexit over the past three years.
“Temperatures are getting particularly extreme now because we are trying to make everyone face reality,” said the source.
“If you have spent three years trying to avoid facing reality and then you have got to face reality, it is inevitably rather an uncomfortable process.”
MPs blocking a Halloween Brexit would be ”taking a wrecking ball to basic democratic politics” with “very, very negative consequences”, warned the source.
Ms Phillips told the Commons that Mr Johnson’s “appalling” comments were part of a deliberate strategy to turn voters against parliament.
“The use of language yesterday and over the past few weeks such as ‘the surrender bill’, such as invoking the war, such as betrayal and treachery, it has clearly been tested, and work-shopped and worked up and entirely designed to inflame hatred and division.
“It is not sincere, it is totally planned, it is completely and utterly a strategy designed by somebody to harm and cause hatred in our country.”
Ms Johnson told Sky News she shared concerns about the consequences of her brother’s words.
“It is particularly tasteless for those who are grieving a mother, an MP, a friend, to say that the best way to honour her memory is to deliver the thing which she and her family campaigned against,” said Ms Johnson.
“I think it is a very tasteless way of referring to the memory of a murdered MP – murdered by somebody who said ‘Britain first’ and was obviously of the far right tendency, which we know will have been being whipped up by this sort of language.
“My brother using words like ‘surrender’ and ‘capitulation’, as if the people who are standing in the way of the blessed will of the people – as defined by 17.4 million voters in 2016 – should be hung, drawn, quartered, tarred and feathered, I think that is highly reprehensible language to use.”
Ms Johnson suggested that her brother’s approach might be a result of advice from aide Dominic Cummings to “be extremely aggressive and to face down opposition from all sides of the establishment in order to secure his position as the tribune of the people”.
In a highly unusual statement at the opening of business on Thursday, Commons Speaker John Bercow said that the “toxic” exchanges in the Commons the previous night were “worse than any I have known in my 22 years in the House”.
He revealed he is considering calls from two of Westminster’s most senior MPs – Father of the House Kenneth Clarke and Mother of the House Harriet Harman – for a formal inquiry into the UK’s political culture, amid concerns over increasingly divisive and violent language.
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