We have been hit by a wave of crime over the past week or two. Not your usual break-ins or graffiti - more of an inside job. Two of our own, so to speak.

There's Adam who adds a whole new dimension to the term sticky fingers. Adam is in First Class and in the middle of a food fetish at the moment. These come in cycles.

Last month it was writing on the windows with crayons every chance he got and before that he had to be watched all the time on break because he kept going outside the gate near the road. Now he's moved on to lunches. And no-one is safe. Chocolate biscuits, oranges, drinks, all fall prey to Adam's insatiable appetite. And this is after he's finished the healthy and very substantial lunch his long-suffering mother has provided.

On average we catch him 50 per cent of the time. Then you tell him to wriggle. Just stand there and shake and eventually some offending item will fall out of his sleeve or down the leg of his trousers or maybe a bump will appear in the front of his jumper and, hey presto!, he'll produce a queen cake.

And as the other kids become aware of his habits, the tendency is to blame him for everything that goes missing around the school. "Adam took it!" has become their war-cry.

And this was the case with the missing Taytos in the school kitchen. A big box stood in the corner - the leftovers from the Christmas party. It was only by accident that we discovered they were gradually, but definitely, disappearing.

We tried everything. We rubbed glitter-glue on the remaining packets hoping to brand the thief. No go. We crossed them with marker and checked all the lunch boxes and pockets the next time one disappeared. Nothing. We decided Adam was becoming a pro at this racket.

But eventually we simply walked in on the robber in our midst. A fifth-classer with nerves of steel. He was standing with his hand in the box in a daring mid-lunchtime raid. We marvelled at his cool. He was taking a huge risk of being discovered while scores of other pupils walked by the room on their way outside.

And then the explanation. Classic. "Ah, sir, I've just checked for you. You needn't worry, no more missing since the last one." What do you do? No use asking this dude to wriggle - he knows the moves too well already.