The meaning of CCTV

'How could images which are so poor in quality be so rich in meaning for us? It's as if a new way of looking at our human insecurity has been invented by accident'

It is the strangest kind of gallery, and it keeps on growing. Earlier this week the latest acquisition was unveiled in British newspapers - four murky and unremarkable shots of a young boy making his way home from the library and doing what young boys do - jumping over benches and scuffing his shoes, subject to the erratic navigation of childish impulse.

It is the strangest kind of gallery, and it keeps on growing. Earlier this week the latest acquisition was unveiled in British newspapers - four murky and unremarkable shots of a young boy making his way home from the library and doing what young boys do - jumping over benches and scuffing his shoes, subject to the erratic navigation of childish impulse.

In one picture he was the main subject - entering a lift in Peckham library with two other boys - while in others he was merely a background detail - a Lowry stick-figure haloed for the curious by an identifying ring. The pictures themselves belonged to an increasingly familiar genre - one instantly recognisable by its artless absence of merit, its pure inconsequentiality. Except we always know what consequences will follow. So although these images lack everything that would usually compel our attention, from fine detail to compositional force, we end up staring fascinated all the same.

The last images of Damilola Taylor, taken just before he was murdered, are a fitting addition to this expanding gallery of loss, destined to sit in the mind alongside the picture of Jamie Bulger being walked to his death, of Diana and Dodi slipping quietly out of the back of the Ritz and into eternity, of Jill Dando pushing through the doors of a local shop before meeting her killer.

The simple existence of these pictures of imminent death shouldn't be surprising any more, since Britain can fairly claim to be one of the most photographed countries in the world - every day literally millions of such pictures are taken, in every urban street and shopping mall. London Transport has 1,400 closed-circuit cameras on the Underground alone, linked to another 1,600 on overground stations. And there are more coming. In 1989 spending was under £200m - 10 years later it had trebled and it is still growing. Last year the Government announced £150m to subsidize CCTV schemes as part of their community crime-reduction programme. What is harder to pin down, though, is why images so poor in quality should be so rich in meaning for us - it's as if a new way of looking at our human insecurity has been invented by accident, a strange and ironic spin-off from the technology of security.

It matters first of all that these pictures are taken by machine - clicking off a frame as often as the capacity of their storage system allows, and inhumanly lacking in distraction. They will photograph vacancy with the same detached efficiency as they photograph something significant, because they have no way of telling the two apart. And since the significance is retrospective anyway, conferred by what is about to happen on what hasn't yet, that is crucial to the service they perform. They can't care about what's interesting at the time, because that's not necessarily what will be interesting a few hours later. But their robotic mindlessness is also connected to the effect these pictures have on us.

There are countless conventional photographs of people who are about to die - almost every assassination or fatal accident seems to create them - but when those pictures have been taken by another human, the purpose for which they were taken often clouds their status as pictures of fate itself: they look like press shots or airport souvenirs and the people within in them are conscious of being watched. In the grainy images of CCTV pictures, by contrast, no one is looking at the lens and what we see, through a glass darkly, is the intimate connection of the unremarkable and the momentous.

They bring home the truth that extraordinary events are seamlessly linked to incidents so banal we wouldn't even turn our heads to look at them.

This is true even when those in the picture are deemed to be remarkable, whatever they are doing. Any paparazzi would have paid a small fortune to gain access to the narrow service corridor in which Dodi and Diana readied themselves to dash for the Mercedes; and someone, somewhere would probably have paid for a picture of Jill Dando doing her shopping, such is the power of fame to gild the banal. But in both cases a machine had the patience or unobtrusiveness to do what a human couldn't - to catch these people at a moment when their glamour was completely in abeyance. The closed-circuit television camera - indifferent to human activity - levels all it sees, making ordinary people out of the famous and celebrities out of the ordinary.

The characteristic fuzz and grain of the image helps, it's true, obscuring distinctions of wealth and even human emotion so that the universal title of victim sits equally well on the young and the old, the rich and the poor. It also amplifies the picture's claim to represent the truth; ever since Abraham Zapruder unwittingly recorded President Kennedy's last moments we all know the rules about picture quality - the better it is the more we must suspect what we see - and that's even truer today, in an age of digital retouching and computer-generated imagery. These images are just too poor to have been faked.

But the quality of these images does something else too. It spreads our sense of vulnerability from what is depicted on to the way it is depicted too. These images look as if they've been rescued, not crafted - pulled back from the surf of noise that threatens to overwhelm them by computer enhancement. In normal circumstances their lifespan is very short - in some cases just 24 hours - after which they will be wiped to make room for new pictures. And at some level, that combination of a fragility which endures and a fragility which does not make them doubly poignant. How can something so inadequate and negligible survive when something so rich and cherished is now irretrievable?

The fact that we know many photographs will outlive us is one source of their effortless pathos but it is peculiarly sharp in these pictures, which exist only as information on magnetic tape, until catastrophe interrupts the ceaseless loop of erasure. They have something of the relic about them, a miraculous shroud or a handkerchief dimly imprinted with a face - a ghostly image of something vital preserved on perishable stuff.

Most importantly of all though - these images play with our sense of time. They offer all of us a power of second sight - not simply because they allow us to replay the past and, paradoxically, look again at something we didn't see the first time. But also because they give us a glimpse of how intolerable and unliveable life might be if we could see into the future - and everyone was shadowed by their fate.

Such pictures rarely show us what happened - death usually takes place in the few crannies between the cameras. Instead they show us what is about to happen. Where most photographs are firmly in the past tense, these exist in a different kind of tense altogether, one to which the time code along the bottom is irrelevant. They exist in the future potential - and because of that they almost always stir in us a fantasy of intrusion, that we might somehow get between this instant and those that are to follow.

The peculiar helplessness we feel in the face of such pictures is a uniquely modern sensation, I think - because it is a cocktail of a quite new power and an ancient impotence. We enjoy a kind of omnipresence now, courtesy of a million proxy eyes. When Concorde crashes we see it, trailing flame, and beyond hope. When the Columbine killers stride towards their death and those of so many others - we can be there to watch them do it. But our capacity to prevent the disaster we can see coming is no greater than it ever was - and feels much less. Those who oppose the untrammelled expansion of CCTV cameras are not slow to point out the irony here - that a device promoted on a dream of prevention so often proves its worth after the event, when it is too late.

"Roughneck can't be bullied" reads the sales pitch for one vandal-proof camera. Unfortunately Roughneck can't intervene, either, when the bullies descend to do their worst. One recent academic study of the introduction of CCTV cameras in Glasgow even suggested that the devices might do less than nothing - crime fell less in the areas with new cameras then it did elsewhere in the city.

Unobserved space continues to shrink almost as rapidly as the rainforest, though, and the one thing we can be certain those new cameras will do is add another picture to this baleful collection. Already there's another unwitting celebrity out there, perhaps even reading this article. It's no use looking to see if you can spot them, because what will make their photographs worth publishing, what will make the rest of us sit and stare and think, is quite invisible now. It's the tiny gap between dull routine and violent death and you can only see it in certain types of photograph.