I felt sickened to the pit of my stomach as I listened to the awful tale. Swiftly I reported what I had been told and the matter was then suitably dealt with.

Over the years I have not forgotten that plunging sense of horror that a teacher was abusing the trust of pupils. It resurfaces now.

The town of Soham is facing up to a most dreadful truth - that Holly Wells and Jessica Chapman may have been murdered by two people whom they knew and trusted. Two people whose roles are well known and important to all of us who teach - a school caretaker and a classroom assistant. My friend who has a seven-year-old daughter tells me that his daughter would be “over the moon” if she was invited into her teacher’s house while out for a walk. Such innocent faith in the adult world.

At the time of writing, along with most other Scottish teachers, I am contemplating my return to school after the summer break. But I can’t get the images of the Soham tragedy out of my mind. These innocent children were found dead, not far from bramble pickers and casual walkers, after an impossibly long fortnight on the hottest day of the English summer.

Desolation. On the television news I watched the ambulance, carrying the broken bodies of these little girls, emerge from a road beside the airfield at RAF Lakenheath. It was late and the vehicle was swathed in darkness. But the biggest darkness lies in the cruelty of the crime and the motivation behind it.

The wicked snatching away of lives of promise, promise epitomised by that last smiling photograph of two happy 10-year-olds with an obvious zest for life. As you contemplate the classes of the new session you will see many such eager little beavers in front of you and they are all vulnerable.

A recent survey by Huddersfield University confirms that most sex abuse is perpetrated by people known to the victim. It may be disquieting to consider it but we must face the fact that anyone who works with children could be an abuser. While, mercifully, what happened in Soham is very rare, there are no grounds for complacency.

Over the past few days I have listened to parents express their absolute outrage at the very idea that anyone who has any contact with children should betray that trust. Trust lies at the heart of our relationships with our pupils.

I passed a box of chocolates round my philosophy students. Without exception they all partook and then I posed the challenge. How can you be sure that I haven’t poisoned these chocolates and that shortly you will all keel over?

The ensuing debate rumbled on with plenty of sharp exchanges. Eventually, however, what triumphed was not philosophical argument but an emotional point from one of my pupils - I know, he said, that these chocolates have not been poisoned because I trust you, Mrs Adams.

Ultimately, then, we must make very sure that everyone who sets foot in a school is not only vetted for a criminal record but closely scrutinised by the rest of us for any signs of behaviour which might threaten the well being of the children in our care.

We may never know the full and terrible truth of what happened to Holly and Jessica but we have certainly had forced upon us the realisation that the people children should fear most are those geographically near them.

The fiend may not be that unknown sex offender miles away but the wolf in sheep’s clothing on the school’s doorstep.

Marj Adams teaches religious education, philosophy and psychology at Forres Academy.