“Kids on the roof again,” yelled a posse of old hands, rushing for the door. The rest of us watched through the staffroom window as the culprits slid down convenient drainpipes, sprinted across the playground and dispersed into the surrounding housing estate. Our school stands at the convergence of several dead-end roads so, if we call the police, our local vandals have a variety of escape routes.

The ones who really worry us are those who don’t run away, but stay to confront and threaten our invaluable premises officer. Like most schools, our buildings are surrounded by playgrounds and fields; there are no houses within screaming range. Even if anyone did hear, they would probably assume that our trespassing adolescents were just being more than usually rowdy.

Local residents complain about the noise, the mess and simply the threatening presence of gangs of youths, and our local bobby on a bike monitors the situation, but still they come.

To a certain extent, we tolerate the local teenagers who congregate in our yard every evening. In this nice middle-class dormitory village, there is nowhere else for them to go, and kicking a ball about the playground seems harmless enough. It’s the older group with less innocent pastimes we worry about - and the detritus they leave behind. A primary school caretaker shouldn’t have to clear up cans, broken bottles, cigarette ends, condoms and vomit before the children arrive, and she certainly shouldn’t have to be afraid to lock up at night after Brownies or aerobics.

Recently, Josie was cornered and threatened by someone attempting to break in. She is carrying on as usual but, as her employers, we have a duty to ensure her safety.

So what can we do? Our first thought was a mobile phone, but wouldn’t that increase the possibility of attack if she was seen using it? A concealed remote control device that she could carry to activate the burglar alarm system might be more effective.

We have already built gates on the more attractive porches, and it is impossible to secure the perimeter. But security lighting might help. We could also request that a member of each user group in an evening stays with Josie until she has finished her rounds and left the site.

We even consider trying to form an alliance with some of our less disruptive visitors. If we turn a blind eye to the skate boarding and football, can they the potential vandals, thieves and arsonists? After all, some of these juvenile delinquents are our ex-pupils. In some ways this is helpful, but it cuts both ways. We know who they are, but they also know Josie, and where she lives, alone.

What happens to those 11-year-olds who leave us so full of promise and return three years later to uproot our trees and break our windows? The parents blame the schools, the schools blames the parents. Me, I blame puberty.

Joan Dalton is a governor in the Midlands.