Right on cue, as the witching hour of Brexit closes in, we are offered an opportunity to reflect on the forces that brought us to this state of national disarray and division. One of the most eye-catching things about James Graham’s drama Brexit: The Uncivil War (screened on Channel 4 tomorrow evening), is that David Cameron proved too dull to make the final draft. The author of this whole catastrophe – the man who, in the interests of party management, put the referendum commitment into the manifesto and as prime minister made it happen – is thus reduced to the status of Gavrilo Princip, the assassin who unwittingly triggered the first world war.

James Graham’s genius is for poking about in the stomach of the beast

What Graham has given us is a timely reminder of the opportunism, disingenuity and ruthlessness of those who jumped through the window of opportunity Cameron opened up. This is a portrait of the kind of people who, depending on your point of view, either think outside the box or set out deliberately to break the rules. Now we are living with the consequences.

Graham’s genius is for poking about in the stomach of the beast. He is less interested in the men in the front row of the snapshots of history than in the people who don’t make it into the picture at all – the party whips in This House, his play about the fall of the Labour government in 1979; a single MP and his constituency in Labour of Love; the editors behind the rise of Rupert Murdoch’s tabloid Sun in Ink. The Uncivil War focuses on the men (mainly) of the leave campaigns. In particular, Graham has homed in on Dominic Cummings, the cerebral obsessive on a lifetime mission to remake British politics.

Being played by Benedict Cumberbatch is the kind of recognition most campaign strategists would cheerfully surrender their contacts books for. Cummings, at least by public account, is chilled about it. But then, he would be. In fact he’s almost certainly delighted. His wife, the Spectator journalist Mary Wakefield, described in an article in the magazine last month how he mumbled something about Cumberbatch dropping by for a meal, the way people do when revealing a monstrous brag (she didn’t say that, I did). By this offhand attitude to celebrity, as well as a starring primetime portrayal of his unblinking focus as a particular kind of integrity, the Cummings “eccentric genius” branding is enhanced. He is just a smart guy with an uncomplicated determination to launch an insurgency. But the trouble with Cummings – and how this is conveyed will be the test of the drama for me – is that he couldn’t give a toss about the relationship between ends and means. If his strategy for winning the referendum screws democratic politics for the foreseeable future, well, that’s for others to worry about.

How well all that anti-establishment posturing worked. Of all the leave campaigners’ tactics – all the breaches of funding laws and the dodgy use of data – perhaps the single most effective strategy was the self-presentation of the leave campaign as outsiders. This was a movement backed by multimillionaire, public school-educated financial traders and fronted by an Old Etonian. The Vote Leave war room was run by a historian with a first-class degree from Oxford (Cummings). Yet it successfully masqueraded for the purposes of the campaign as the authentic voice of ordinary Britons ignored by a contemptuous elite. There’s nothing wrong with a campaign composed of people who could, if they chose, access all the inner sanctums of power. But the disingenuity sticks in the throat.

The shameless misinformation that Cummings and his associates propagated hardly constitutes the first assault on the rules of conduct on which parliamentary democracy depends. It’s just that their techniques were infinitely more brazen and dangerous than anything that has gone before. The Blair-era news management operation, which arose as in reaction to the tabloid hounding of Neil Kinnock, seriously undermined faith in political discourse, but Alastair Campbell and Peter Mandelson never claimed to be acting to restore democracy while all the time chewing it off at the roots.

Their audacity was best summed up in the single, Cummings-crafted message, “Take back control”, implying that control – sovereignty – had been frivolously, cravenly surrendered by an effete political class for no discernible reward. The notorious pledge of £350m a week to the NHS was the symbol of what restored sovereignty would deliver. It was a grossly misleading figure that crowned a campaign based on deceit. No one imagines we live in a world where politicians never dissemble, but nor did we imagine that they painted deliberate untruths on campaign buses.

Looking back from our present dismal vantage point, there is also a second sleight of hand that is rarely discussed but which Cummings plainly understands, and which may, in the long run, be even more damaging. Tim Shipman, whose All Out War is the definitive account of the referendum campaign, quotes a source on two kinds of political operators: “people who see the population as they would like them to be … and people who see the population, ruthlessly, as they actually are”. It was, said the source, the difference between wishful thinking and winning. Remember the Leave.EU “breaking point” poster showing a long line of refugees. The “uncivil war” was fought by leavers appealing to our worst instincts.

The way we talk about each other, and in particular the way politicians represent their voters’ views and ambitions, shapes how we think about ourselves. The great achievement of the postwar era was to create a national identity that at least aspired to be compassionate and meritocratic. It wasn’t entirely true, but these were qualities generally considered desirable enough to be recognisable. Cummings and his wing men on the shabby side of the leave machine, impatient with the muddle and compromise of with representative democracy, gave voice to a national identity that is inward-looking, selfish, sometimes xenophobic, and in some quarters downright racist. By defining one cultural tribe, a second was created in opposition to it. And a country split in two is a country where the negotiation central to democracy will always struggle. Dull and boring Cameron facilitated this uncivil state of affairs; it was Cummings who delivered the war. Watch Graham’s drama and weep.

• Anne Perkins is a writer and broadcaster and former Guardian correspondent