How far back do we go to identify the root of the rot?

Too far to fit into this column, so let us travel just four years ago to one of Boris Johnson's many unedifying episodes. He and the word "sorry" were hardly kissing cousins, but it nevertheless provoked fury to hear him refuse to apologise for his language regarding the murdered MP Jo Cox.

The former prime minister dismissed concerns about his use of inflammatory rhetoric - calling the Benn Act passed to avoid a no-deal Brexit the "surrender bill" - and his telling an MP her concerns about aggressive language were "humbug".

Even his sister criticised Johnson when he said the best way to honour Ms Cox was to "get Brexit done". For context, the MP, who was killed in 2016 by a far-right extremist, had campaigned against leaving the EU. Her killer shouted "Britain first" as he stabbed and shot her.

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Johnson was repeatedly called on to apologise, including by Labour MP Karl Turner, who said he and other MPs had received death threats.

Humza Yousaf will no doubt balk at an immediate pivot from Johnson's "surrender bill" to his own conduct but, as we experience another period of heightened tensions where politicians are in fear for their safety, the First Minister should have thought twice about capitalising on a newspaper front page emblazoned with the word "traitors".

The controversial Press and Journal splash took aim at Labour and Mr Yousaf shared a picture of the cover on X/Twitter in an attempt to undermine Anas Sarwar and Keir Starmer.

Rigorous debate is vital but the use of "traitors" was an open goal for the opposition to level criticism about toxic and divisive language.

In a week of persistently unedifying conduct, the king of division has been, of course, Lee Anderson. He has had the Tory whip removed for Islamophobic comments in which he stated the Mayor of London has been captured by Islamists who have control of the capital.

Anderson, uncowed, has been merrily posting pictures of pints on X/Twitter. In one, he claims a woman called Sue left him a fiver behind the bar for a drink. "A night cap," reads another post with a photo of a glass of Madri. Due to all the positive feedback, he wrote, now he's back in London, "I've decided to have another pint to get me ready for a long week."

Not a very effective job from the old Islamists there, if alcohol's still readily available.

Anderson might have got away with it had he stuck to a general statement and not named names; he is far from a lone voice. Robert Jenrick, a former cabinet minister, said Britain has "allowed our streets to be dominated by Islamist extremists". Penny Mordaunt, leader of the House of Commons, replied that she "could not agree more".

Rishi Sunak has removed the whip from Lee Anderson. What will he do next? The Prime Minister moved swiftly enough - certainly faster than Keir Starmer in dealing with Azhar Ali's anti-semitic comments at the Rochdale by-election - but will Anderson see the whip returned?

Sunak promoted him to deputy party chair as a sop to the right of the party, which was bearing down on his leadership. Anderson resigned over the Rwanda bill, saying it was not tough enough.

That he holds Islamaphobic views and has no qualms about expressing them should hardly be a surprise to the PM; all parties know what they're doing.

Sunak might further wish to remove the whip from Liz Truss and Suella Braverman. That Truss is appearing at pseudo-Trump rallies and staying silent when interviewers praise disgraced far-right agitator Tommy Robinson is unconscionable behaviour for a sitting MP.

Braverman's Telegraph column the day after the Commons debate was peppered with the language of aggression - Britain must not admit "defeat", there is a "battle" to be won.

Jewish and Muslim communities talk of the fear they experience at new waves of anti-semitism and Islamophobia in response to the Israel-Hamas war.

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We keep making reference to dog whistle statements but when it's this loud it's just a whistle. Sunak must show he can deal with inflammatory rhetoric from the right of his party.

We forget, when the most publicised picture is so bleak, that there are a great many decent Conservative MPs who despair at the state of the party and despair at the headlines. Those decent MPs are who should also speak up.

This climate has been created both within and without politics and the current culture of fear is - if we are to believe the motivations of Speaker Lindsay Hoyle - affecting the democratic process.

Last Wednesday's scenes in Westminster were, as has been repeated ad nauseum now, unedifying. Keir Starmer was given a reprieve from rebellion yet while Labour may feel it won the battle within Westminster, all involved lost the fight for the respect of everyone outwith.

The UK is in the painful position of having seen two politicians assassinated within the past 10 years. Jo Cox and David Amess are always named but we must not forget Keith Palmer, the unarmed police officer who was killed in 2017 as he tried to stop the terror attack on Westminster.

The MP Mike Freer saw his London constituency office firebombed at Christmas. The Sunday papers were full of stories about MPs being given panic alarms and additional security in response to threats.

Last week staff at the constituency office of Paul Sweeney and Pam Duncan-Glancy, Labour MSPs, called police because they felt afraid of protestors at the building. Protestors say they were there peaceably and eyewitnesses say there were no real cause for concern.

Mr Sweeney has backed his staff, insisting they were genuinely afraid and the sense of threat was real. Protest is beautiful and the right to it must be sacrosanct but it speaks volumes - not least due to the frenzy created by Lindsay Hoyle's decision in parliament last week - that political staffers feel such disquiet in their workplace.

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We lose decent, talented politicians and staff to this fear. Just Stop Oil has now said it will challenge MPs outside their homes, while Gaza protests have happened outside MPs’ houses. There is a literal and figurative boundary being broken there.

There are many strands to this fevered state we're living in. Britain has had a long run of gutter politics. Voters are angry, they are disillusioned. Brexit removed an easy bogeyman for lazy politicians to project blame onto and so they reverted to targeting migrants, asylum seekers and, now, anyone generically "foreign".

Because much of politics has become a battle of identity, people believe they are fighting for the soul of who they are, a state that does not lead easily to moderation. There seems, crucially, no clear end in sight.

Following the murder of Jo Cox, there were calls for a more collegiate, empathetic politics. There were calls for kindness. Horror at the death of a woman killed in a brutal and cowardly attack should have been a turning point but it was not. Instead, further nastiness has infected the system.

There is little to be proud of and much of which we might be ashamed.