‘For days past there has been no real news and little possibility of inferring what is really happening,” wrote George Orwell in his diary, on 28 May 1940. “Last night, E[ileen] and I went to the pub to hear the 9 o’c news. The barmaid was not going to have it on if we had not asked her, and to all appearances nobody listened.”

That was the second day of the Dunkirk evacuation, and just hours after Churchill had made his speech to the Cabinet, which said: “If this long island story of ours is to end, let it end only when each one of us lies choking in his own blood upon the ground”.

By 28 May Belgium had surrendered, the French army collapsed and fighter cover for thousands of troops massing for evacuation on the beach at Dunkirk was exhausted. Yet an educated insider like Orwell had to guess at what was happening and most people in the country didn’t care.

We’ve had two biopics of Churchill in the last 12 months and a spectacular movie about Dunkirk, but none of them really captures the peril Britain was in – and none of them adequately frames Churchill’s heroism for what it was.

My grandparents – miners who had lived through the 1926 general strike – couldn’t wait to see the back of Churchill and voted him out at the first opportunity in 1945. That was because he had been on the wrong side not just of history but of statecraft for most of his political career: wrong at Gallipoli, squandering the lives of 45,000 troops through bad planning and hubris; a vindictive class warrior, from Tonypandy in 1910 to the general strike and an outright racist in his rationalisation of imperial rule in India.

Churchill had told Mussolini that the fascist dictator had “rendered a service to the world” by destroying the Italian labour movement. “If I had been an Italian, I am sure I should have been whole-heartedly with you from the start to finish in your triumphant struggle against the bestial appetites and passions of Leninism,” he announced, during a visit to Italy in 1927.

On the principle that all good stories are about redemption, it should not have been hard to turn Churchill’s triumph of May 1940 into a cracking yarn – and Darkest Hour, which opens this week starring Gary Oldman, by all accounts does a decent job. The problem is, even now few people watching these movie portrayals understand what was at stake during the Dunkirk crisis. And that is because so few retellings of the story are prepared to confront its class dimension.

Class divisions and antagonisms were enormous in the Britain of 1940. The scale of elite collusion in the effort to appease Hitler was unknown by most members of the public. The scale of the military disaster unfolding was also unknown. And, as Orwell repeatedly recorded, very few people were interested in news about the war. Unlike today, where tabloids and broadcast news programmes deliberately dumb down news content to keep a mass audience engaged, journalists in the 1940s kept it straight, self-censored, boring and therefore largely unintelligible.

The front page of the Daily Mirror, for example, on 28 May 1940, assured its readers that the Germans had been “checked” in a “big battle”. Page two led with a story about the French “generalissimo” Weygand meeting King Leopold of Belgium; the Reuters correspondent captured the detail that Weygand “entered a village inn and ordered a cup of coffee and an omlette” but omitted the fact that Leopold had just surrendered the entire Belgian army to the Nazis.

When tens of thousands of troops returned, defeated, the national mood radicalised. Orwell’s diaries describe May 1940 as the beginning of a “revolutionary situation”, which would unfold as London and other cities were smashed by the Luftwaffe. A month after Dunkirk, Orwell wrote, privately, that “the belief in direct treachery in the higher command is now widespread, enough so to be dangerous …” Though he discounted stories that the officers at Dunkirk had fled, leaving ordinary soldiers in the lurch, he recorded their widespread acceptance and understood its political significance.

Churchill’s choice to fight – even though, as the writer of the Oldman movie claims, he veered dangerously close to the idea of a compromise with Hitler – was the result of a patriotic calculation. If you don’t fight, you lose the empire, was one line of argument. The other, implicit, but understood above all by the Labour moderates around the Cabinet table of the all-party coalition – Clement Attlee and Arthur Greenwood – was about domestic politics.

Boris Johnson, in his recent biography of Churchill, constructs a convincing alt-history around the question: what would have happened to the world in a “non-Churchill universe”? Nazi tyranny across Europe is the answer – but Johnson can’t quite bring himself to complete the picture by asking what it might have done to British politics. The answer is, they would have exploded. In a non-Churchill universe, the Labour leaders, under pressure from their mass base, might never have joined the National Government. They would certainly have broken with it if, under cover of a semi-press blackout, the British government had handed Malta, Gibraltar and some African colonies to Germany and then sued for a separate peace. To sell that peace to the public, the entire supercilious apparatus of the media, monarchy and civil service would have been deployed.

Churchill’s genius in 1940 was not just that he understood the military situation, but that he understood the dynamics of the British class system and what kept working-class radicalism in check better than any Conservative member of the cabinet.

Both the current Churchill biopics portray him as a flawed elitist, past his prime, drawing on emotion and willpower to make an otherwise inexplicable break with his blundering past. Meanwhile the Dunkirk movie portrays Britain as a kind of sepia postcard, in which people manning the flotilla boats stand like model figurines against fragments of Nimrod from Elgar’s Enigma Variations. Though all three films are eminently watchable, it is important to understand that a false reality is being constructed, in which class conflict, ignorance and the deep pro-fascist sympathies of the large sections of the British elite are edited out. Once you factor them back in, the redemptive character of Churchill’s actions become all the more impressive.