Ninety days’ suspension and a lifelong ban from a pass to enter the Palace of Westminster. This is the punishing verdict for the only prime minister ever found to have misled parliament. Naturally, Boris Johnson lashes out at the privileges committee judgment as a “final knife-thrust in a protracted political assassination”, designed “to find me guilty, regardless of the facts”. All the committee’s painstakingly careful yet eye-popping evidence bounces off him, as he treats the detailed accounts of six (plus another 16) Downing Street parties, and the lies he told, with total contempt. Furious self-pity, paranoid victimhood and faith in his golden merit is true to form. This verdict should be the stake through the heart of a disgraced career. Anthony Seldon and Raymond Newell already produced enough devastating evidence in the biography Johnson at 10 to prevent any conceivable resurrection of this monster, you would think. At a literary event this week, Seldon signed my copy with: “A story about the worst prime minister in (modern) history – rotten to the core.” The hypothetical punishment was multiplied for his complicity in a “campaign of abuse” against the committee, which he derided as a kangaroo court. His smears today were expected, claiming the findings that he deliberately misled the house were “rubbish”, and “a lie”, calling it a “deranged conclusion”. He said some of the committee’s arguments were “a load of complete tripe, and that “this report is a charade”. But don’t imagine these are the final ravings of a desperate man as he sinks into a hell of his own making. No, there is nothing reckless or uncalculated about this Trumpian tactic. He does not for one moment expect to convince the likes of you and me, or any half-rational observers, but to give ammunition and hope to his little platoons of supporters, about two dozen in parliament and many more among the Tory membership, who might, just possibly, get some future chance to select him again as their leader. There is nothing wild about Johnson’s flamboyant rejection of criticism, as it gives his many foghorns in the media a supply of ammunition to keep the Brexit fires burning, saluting their hero as the prince over the water. This is civil war. Their enemy is Rishi Sunak, the usurper in Downing Street, who even now is wrongfully enjoying Johnson’s gold wallpaper. The remainers, lefties, wokerati and metropolitan elite are now forgotten enemies for Johnson and his platoons, who focus all their fire on their own frontbench. That war may fizzle out, when you look at the quality of politicians rallying to the tattered flag of Johnson’s cohort – Michael Fabricant, Jake Berry and Jacob Rees-Mogg. But they can still inflict salvoes of unfriendly fire. Nadine Dorries is trying to time her byelection for maximum damage. Yet in this bizarre Conservative party nothing is impossible, so this embittered platoon may yet turn into more than revenge-seekers. If Sunak’s March budget tax giveaways fail to bribe enough voters, we already know that a panicked Tory party, which gave us Johnson and then Liz Truss, is capable of absolutely anything in a frantic attempt to hold on to its vanishing seats. Here’s the world they inhabit: the Sun reminds us of the insane power of the tiny Tory membership. When it comes to the free vote on the floor in the Commons on Monday, each Tory MP will have to decide for themselves whether to back the privileges committee report, or express continuing support for Johnson by rejecting it. The frightening anti-democratic threat, expressed by a senior Tory, is that any Tory MP who votes for the report “will be having some serious issues with their associations and wouldn’t be remotely surprised if they were given the boot”. So here we are in full Trump territory, where intimidation by a small group of Johnsonite Tories can terrify their MPs into backing him. They are deluded. The idea that the Johnson magic of Brexit and the 2019 election could be resuscitated is a phantasm. The public wouldn’t have it. They view the idea of his resurrection as a joke. Fuel was added to his funeral pyre this week when the Covid inquiry opened with a sad cortege of heart-breaking witnesses talking of what happened to them and their families. They never visited the sick and dying. Now, they are left to mourn their obedience to rules ordered by Johnson at his nightly press conferences. The bereaved will always be there, like the parade of ghosts haunting Richard III on the eve of battle, reminding everyone that this was never a minor matter of a few parties. This act of contempt, of misleading parliament, might seem an arcane oddity to many voters witnessing so many extravagant non-truths and factoids hurled about the House on an ordinary day. But a mother who was stopped by the police from saving her suicidal daughter is the kind of Covid story that, once heard, can never be forgotten. That Johnson and his coterie can imagine he has been hounded from office on trumped up charges shows just how unfit for office they all are and always were, and how far removed their lives are from the experience of the rest of the population during those lockdown months. This was indeed the “worst” prime minister, the most unfit and yet, terrible though it is to admit, probably the most important. His short term in office has left the deepest and most enduring legacy that will scar the history books when other leaders are long forgotten. No other prime minister in my lifetime has inflicted such permanent and crippling damage, dividing and diminishing the nation with a Brexit he didn’t even care about. Margaret Thatcher’s harms are many and searing, but they can be undone, and it looks as if many soon could be. Brexit is a deeper laceration. It will forever leave a mark as the most abrupt and pivotal point in the nation’s decline. Despised abroad, with a shrinking GDP and a loss of foreign investment as well as respect, Britain now finds itself alienated, alone, and sliding downwards on just about every league table. Johnson did this, the political wizard who cast a spell over the voters with his outrageous lies and promises. His cunning verbal wit – and even the seductive falsities he peddled – were part of his charm. This was his only talent, and it was lethal. Polly Toynbee is a Guardian columnist