Was Ken Barlow really Jack the Ripper?

A question for you. Could Ken Barlow, Coronation Street's bleeding heart liberal, actually be Jack the Ripper? Don't be fooled, when you're dealing with violent men, by the veneer of civilisation – that was one of the messages of Patricia Cornwell's Stalking the Ripper, shown on Omnibus the other night. Meanwhile, in the same week, Ken Barlow reverses half a century of educational thinking and knocks a schoolboy flat. See what I'm getting at?

There's a bit of violence in all of us, and given the inducement, there is potential for a lot more. Art is forever telling us this. If you don't enter into Raskolnikov for two or three hundred pages, there's no point in reading Crime and Punishment. Never mind the urgings of the good citizen in you to do otherwise, in art you have to unshackle the murderer who is also you. Ken Barlow isn't Raskolnikov, nor is Coronation Street Crime and Punishment, but the soap became art of sorts the minute Ken Barlow let his nature off the leash at last and broke Aidan Critchley's nose.

Good name, Aidan Critchley. You'd be itching to hit someone with a name as smug as Aidan Critchley whatever kind of pupil he was. Just as you can't wait to kick Uriah Heep. Art, you see. Art lets you indulge these feelings.

Ken Barlow lands one on Aidan Critchley, anyway, and you could hear the cheers above the rooftops. This wasn't only an aesthetic response, I grant you. There isn't a sane adult living (bar Barlow himself) who believes there are absolutely no circumstances in which a teacher can be allowed to strike a pupil. Create a climate in which the old run scared of the young, and heaven itself will revolt.

Even as schoolboys ourselves we knew that to be the truth, that there was a right and wrong ordering of things. Yes, we vowed a silent and a bloody revenge whenever the slipper or the cane came out, but let a bad boy cheek a frightened teacher, and our hearts stopped. Nothing at school was ever more upsetting than that – the spectacle of a child humiliating a man.

So it wasn't only cheering at the righting of a wrong I heard when Ken did what he should have done months ago; nor simply the sweet music of a brat's nose breaking; it was also the air escaping from an ideology that has made us all afraid of asserting anything for decades.

Set art against ideology and art wins every time. Here at last was narrative vindication of all those years of watching Ken Barlow disappear into the fundament of his own self-righteousness. For such a man to lose his rag, for such a dedicated liberal to act illiberally, how great must have been the provocation. And faced with such a provocation – dramatically realised, as we used to say at university – what worth our principles? Ken Barlow knows where he stands: he shouldn't have done it. But we who have been complicit in the act's unfolding, acknowledge the promptings of another truth.

As for Jack the Ripper – or rather the painter Walter Sickert, for according to the crime writer Patricia Cornwell they are the same – there is both more and less to be said. Somewhat more gratuitous than Ken's, the Ripper's bloodlust. But not to be confused, however far the resemblance can be stretched, with the extremities into which an artist looses his imagination. Walter Sickert painted murdered women, that started Patricia Cornwell's "crusade", that was why "he was, like, pulsing on my radar screen."

Thereafter, as she flies in armies of experts in DNA and body parts and the like, she begins to construct a case – tenuous even by the experts' own admission – based on more scientific evidence. A scraping here, a similarity of tissue there, and the likelihood that the suspect had a problem with his penis, that's to say as good as didn't have a penis at all. Telling, that. Take a man's penis away from him and no woman's throat is safe.

But it's the circumstance of Sickert's art that keeps pulsing on Patricia Cornwell's radar screen, an aesthetic distaste not just for the painting but for the man who painted it. You know what's coming. Looking's coming. The act of murder anticipated and then duplicated and then lovingly remembered in the act of contemplation.

A number of male artists have bit the dust in recent years for "predatory" contemplation of the female form. Dégas copped it, Lucian Freud isn't entirely in the clear, now it's Sickert's turn. Only this time the act of contemplation isn't just metaphorically rapacious, it's a commemoration by the perpetrator of the real thing. Bingo! We have him. The male artist as literal, never mind figurative, dismemberer of the woman.

Well, who am I to say who was or wasn't Jack the Ripper? But Sickert's interest in a serial killer no more makes him one than does Patricia Cornwell's. Here was the irony of her demonstration: Sickert was steeped in the subject, she argues, but nothing like as obsessively steeped as she is; Sickert loved blood and guts, she insisted, but it was she who hacked away at home-made cadavers, plunging her arms up to her elbows into as much liver and kidney as would fit into her shopping bag.

Sick? As a parrot. Never a smile, never a break from the automatic rifle fire of her delivery. And when she stared at rare footage of Sickert in white-bearded old age, starting from the "evil" in his eyes, we could not forget the photograph of her father we'd seen earlier, the father who'd walked out on her, white-bearded as Father Christmas.

Psychologically obvious? You bet. And that might very well have been the point of the exercise. Deranged man-hating meets deranged woman-hating. Except that Sickert's art doesn't look remotely deranged to me. It just takes us, as art should, where we might not otherwise willingly have gone. Bloody? Yes. But then we are in blood steeped so far, as Ken Barlow has been heard to observe.