Last Night's Television - It's Only A Theory, BBC4; Blitz: The Bombing of Coventry, BBC2

"Devastating bombs were dropped on innocent families," said the voiceover at the beginning of Blitz: the Bombing of Coventry. As opposed to what? Mildly disconcerting bombs on families who had it coming? Bombs that rained a confetti of marshmallow on families that were a legitimate military target? Devastating is what bombs do, isn't it? And perhaps even the less than innocent families should be spared one coming through the roof? Along with the information that "reconstruction" would be employed in Ashley Gething's film about the 1940 raid on the city the phrase made me a little wary. In fact, it turned out to be a beautifully judged account of that night, its fillings out of the eye-witness accounts so carefully done that you were hardly aware they were there at all. A man would describe finding a women feebly clawing the rubble from her body and you assumed you could see it because his account was so vivid, not because the programme- makers had spent a busy afternoon on a sound-stage with dummy bricks and a smoke machine.

The original title for the programme appears to have been "Coventrated", the term Joseph Goebbels coined to describe an attack so total in its destruction that it effectively wiped a city off the map. That was the theory, anyway, and it was a theory that terrified Britain's war planners, who'd looked ahead at the prospects of a bombing war and assumed that civilians would crumble almost instantly. Government psychologists predicted that adults would regress to infantile forms of behaviour and mass psychosis would break out. Churchill hadn't exactly been blithely encouraging about the importance of this phase of the war – "upon this battle," he growled, "depends the survival of Christian civilisation" – but he had no certainty that civilian morale would withstand the impact of high explosive.

At first, it looked as if the psychologists were right. One of the participants recalled angry rows breaking out in the bomb shelters over trivialities, such as exactly how many explosions had been heard. Others reported hysteria and fainting in the streets as people emerged after 16 hours of bombardment to discover the city they lived in utterly destroyed. Lines of refugees – instantly familiar from newsreels of European conflicts – formed on British suburban streets. "I couldn't see the phoenix rising from the ashes at that time," said one man, "I could only see the ashes." But then, after a few hours of helpless shock, people began clearing lanes through the masonry and the King turned up, a close brush with monarchy being somewhat more potent back in 1940 than it is today.

The archive footage and photographs were startling, knitted into a very effective Heinkel's-eye-view map of the old city. But as always it was the human recorders who retained the tremor of shock. One woman's voice broke as she described her mother's dismay on hearing that the cathedral had been destroyed, grief for a familiar old building piercing even deeper than sorrow for unknown people. Another man recalled the last moment of his father's life, blocking the door of the Anderson shelter to protect his sons from a blast that arrived with massive impact but no sound. And another survivor described how the German bombers had stitched destruction across the city in one direction and then returned later to do the same thing at right angles: "It was like darning a sock," he said, a homely image for a terrible thing.

"Nowadays, it seems like experts give birth to a new theory every few minutes," said Andy Hamilton at the beginning of It's Only a Theory. I don't know about that, but if so they're at least matched by comedians pupping new comedy-panel shows, most of which, sadly, are doomed to be tied in a sack and dropped into the swiftly flowing river of television oblivion. I'm guessing that It's Only a Theory isn't going to make it to adulthood, because it's very difficult to work out what it's for or how it's meant to work. A panel of two gag merchants (Hamilton and Reginald Hunter, who can both be funny) are joined by a celeb guest (it was Clare Balding this week) to offer peer group review on the theories of scientists and experts who quite like the idea of being on telly. They then say whether they've been approved or rejected, though it isn't clear on what basis they arrive at this decision and nobody gives a damn anyway. Last night, they batted around the ideas of a gerentologist who thinks the first 1,000-year-old person has already been born and a psychologist who believes that we shouldn't medicalise sadness – these two topics provoking a meandering and underwhelming blend of flippancy and bland earnestness. It isn't that the machinery doesn't work, it's that they completely forgot to put the machinery in. I can only hope it isn't distracting Hamilton from writing more episodes of Outnumbered.