Just why is the ITV drama Mr Bates vs the Post Office having such an impact? After all, the story of how Post Office sub-postmasters were wrongly accused of stealing money due to faulty accountancy software is hardly unknown.

If drama is meant to surprise, where is the big reveal? We already know that bankruptcy and imprisonment, divorce and in some cases death followed the Post Office insisting that its Horizon accountancy software created by ICL/Fujitsu could not be wrong; insisting that sub-postmasters whose accounts showed losses would have to pay the money back.

We know this, or some of it, thanks to old-fashioned journalism by Private Eye and Computer Weekly, to BBC Radio 4, to the Sunday Times and to Nick Wallis, author of The Great Post Office Scandal.

Yet perhaps we don’t really know anything; or only in that way we have of half-knowing something before our attention wanders to whatever comes next.

That is why Mr Bates vs the Post Office is such a good and powerful drama. It makes us sit up and pay attention; it makes us spit with fury at the raging miscarriage of justice. And it makes us/me cry.

Writer Gwyneth Hughes wraps 20 years of suffering and angst for the accused sub-postmasters into four crisp episodes of mainstream drama. Not even four hours, thanks to the adverts.

The details are complex and tangled, knotted and barbed. Yet the telling here is simple, shocking and deeply human, especially in the central performance of Toby Jones as Alan Bates, the unyielding sub-postmaster who became an indefatigable cataloguer of wrongs and a doughty campaigner.

His performance, alongside that of Monica Dolan as another victim who fought back, is naturalistic and truly believable. Jones almost says more with the creases of his face than his voice. Watching those anguished and bitterly wry lines at work is to see a quiet storm gathering.

That’s why this drama is having such an effect. It looks again at this heartless British scandal and puts to the fore the human emotion, the despair, the shame and the sheer bloody unfairness of what happened thanks to the deeply underhand behaviour of the Post Office management.

In the wrong hands this could have been dull or worthy – instead, this tale of injustice is as gripping as any thriller, as emotional as any tragedy.

And these are real stories. Lee Castleton, the Bridlington sub-postmaster whose two-year legal fight saw him bankrupted, was pursued for £321,000 costs by the Post Office, seemingly for his temerity in standing against their might.

Lee, who is played by Will Mellor in the drama, told last weekend’s Yorkshire Post – “I am just so grateful. Finally, people are listening to the sheer trauma that happened in people’s lives.”

Much of anger is now being directed at Paula Vennells, the former chief executive of the Post Office. That is perfectly reasonable, as too is the petition (1.2 million signatures and rising at time of writing) demanding she be stripped of her CBE.

I’d happily see her denuded of that title. Yet the very giving of honours to such high-altitude businesspeople is problematic. Members of that too-elevated class go from one extravagantly rewarded role to another, seemingly unaffected by failure or past embarrassment. They are paid more and more with scant regard to how their work has affected those toiling on the lower slopes.

Yeah, snatch back that title if you wish; better, though, to think again about who we given such baubles to.

And members of the government suddenly joining this chorus to express their anger has about it the nettle-sting of hypocrisy as the government owns the Post Office. This scandal has been running for too long for Rishi Sunak to suddenly discover his convenient outrage.

As for Alan Bates, as portrayed here by Toby Jones, he is the patron saint of stubbornness, the great British awkward sod who never gives up. And he hasn’t given up yet, as the fight for compensation continues.