Join me, won't you, on a journey back in time to a Saturday in 1972. Arsenal are playing Liverpool at Highbury when suddenly one of the linesmen drops to the ground with a twisted leg.

Because no one thought to pack a spare official in those days, abandonment seems the only possible outcome. More in despair, one feels, than hope, the call goes out over the Highbury Tannoy: “Is there a lino in the house?” (Or words to that effect.) And who should suddenly bounce out of the tunnel in a commandeered tracksuit? Why, none other than Jimmy Hill, bravely overcoming the intense personal aversion to the limelight that has characterised his career. Hill, a qualified referee, sees the game out, Arsenal and Liverpool draw 0-0 and civilisation continues on its course.

Imagine that happening today in a big - indeed, any - televised game. Imagine a vacancy suddenly falling open for a freelance assistant ref - tracksuit and flag supplied. Whose hand would be up in the air? Not even Hill's, I would imagine. And not just because, since Saturday, the chances of getting beamed by a coin aimed at Harry Redknapp appear to have risen slightly. Worse - possibly more painful, even - would be the almost certain prospect of getting unfairly shredded by television.

Take Manchester United v Celtic on ITV on Tuesday. Thirty minutes in, Dimitar Berbatov scored from a few inches offside. Who noticed at the time? I didn't. Clive Tyldesley didn't. The ITV commentator's instinctive reaction was to erupt, in his usual style, like a sleeping dog that has just been trodden on and bark not “Oi, lino!” but “Berbatov! Goal!” Tyldesley went on: “It was very well taken. He's beginning to score freely now in the red shirt.”

Then a replay was shown and Jim Beglin, sitting beside Tyldesley in the commentary box, abruptly changed tack. “Wow,” he said. “It's offside and the assistant has missed it.” Tyldesley and Beglin piled in. They dug out the official for failing to see with the naked eye something that they didn't see until shown the incident again from two angles, in slow motion (and, quite probably, with additional prompting from the production staff, via their earpieces).

“All the evidence there suggests it's a goal that should not have stood,” Tyldesley formally declared. “Berbatov's goal is the difference,” the commentator later reported, “but it's a very dubious goal . . . courtesy of what looks like a dreadful decision.”

Dreadful? Where did that come from? Yet at half-time, the eerily smiling Steve Rider referred darkly to Berbatov's “controversial finish” and, at this point, you could see the matter spilling over into News at Ten. Bong! “Shares in freefall again.” Bong! “Blind linesman runs amok at Old Trafford.” Bong! “And why Happy the hippo won't be home for Christmas.”

It gets worse, though, because, in the second half, Berbatov scored again. “Easy as you like for Dimitar Berbatov,” Tyldesley shouted. “Ooh . . . wait a minute.” Again, the replay was on and again, in the clear light of slow motion, Berbatov seemed to be fractionally ahead of the defensive line. “Technically it's another mistake by the officials,” Beglin announced. “It's another dubious goal,” Tyldesley chorused.

Afterwards, Gabriel Clarke stopped Sir Alex Ferguson in the tunnel to tell him that both of Berbatov's goals were “just offside, we think”. Ferguson almost stopped chewing for a moment before pointing out that it's “good to get a break for a change”, thus placing the incident in the context of United's long history of judicial hardship. But what's any manager going to say? “Just offside? Really? But that's unacceptable. Let's go out and replay the game immediately.”

Thus does the pot get stirred, though, and, after the match, Andy Townsend fearlessly used the electric pen of destiny to draw the yellow line of justice in the “shaded area” of truth and grudgingly declared both those decisions “marginal”. Absolutely.

“Un-spot-able without a microscope,” might be another way of putting it.

Only Steve Bruce, the studio guest - who, incidentally, with each passing day, looks more and more like Bill Clinton around the time of the Lewinsky scandal - seemed genuinely interested in flying the flag for human understanding. “We're talking really, really slight margins,” the Wigan Athletic manager protested.

But some people are clearly dwelling so far inside the televised packaging of football, with its push-button ability to break incidents down into molecules, that they have forgotten that the game only happens in real time. So who'd be a lino - already required to enforce a law that essentially requires you to have eyes on two places at once, only for television to come at you afterwards with what Rider smugly referred to as “the definitive slide rule”?

Graham Taylor is always bashing on about England manager being the impossible job. He's wrong. The impossible job is assistant referee, and the lords of hindsight on television don't make it any easier.