“You call a child’s name on the register but the child is absent. A few days go by with no note or phone call. Attempts by the school office to call home and other contact numbers draw no reply. The home visitor calls to find house empty.

“By now the rest of the kids in the class are telling you that so-and-so has left and moved away. No idea where though. The child stays on the register being marked as absent perhaps for as long as two terms. Finally in the post comes a request from another school on the other side of the country for the child’s records. Now we know where they have gone...”

This is a scene familiar to many teachers. But, as this correspondent to the TES website adds: “What would happen if the parents decided not to send the child to a school? What if the child was no longer around? Who would know?” Worries about the “loose system” that permits schoolchildren to disappear without trace are a recurrent concern to many involved with education. Such children often return to official view only when their parent enrols them in another school - perhaps to disappear again after a few days, too soon for their records to catch up with them.

“There does seem to be a huge hole which these kids drop into,” says another website correspondent. “It was no surprise to me when the details about Fred West’s kids came out.”

“Surely,” says yet another, “with all the technology available today, someone could set up a central register so that concerned teachers and social workers could follow up these children?” Children who disappear from the system fall into many categories. One of the largest has traditionally been pupils excluded from school.

Missing Out, a report by the Audit Commission two years ago, found that a third of local authorities were unable to trace all their permanently-excluded pupils six months after the academic year in which they were expelled. But the current Government push - to prevent exclusions and to provide alternative education for excluded pupils - means this is one group that is now much better tracked than before.

Long-term truants remain a problem. The most intractable group is the 14 and 15-year-olds, for whom it is almost too late to return to school. Connexions, the Government’s new one-stop advisory service for 13 to 19-year-olds, may help to keep track of this group.

Other categories that can fall through the net are the itinerant poor - including travellers’ children - and asylum seekers. One school that has plenty of children who appear and disappear suddenly is Northdown primary in Margate.

On a recent Wednesday - the day on which prospective new pupils are shown round - there were five hoping to join the school in 10 days’ time: one with English as an additional language, two children of travellers and two other casual admissions. The school’s educational welfare officer, meanwhile, is trying to track down pupils who disappeared on holiday to Ireland and Scotland in the summer and never returned.

“The parents just drive off,” says the head, Jackie Cox. “Now I’m just waiting for a school to contact me.”