Sometimes you take an instant dislike to someone. In other cases the enmity builds up like plaque. My worst parent fell into the latter category.

Indeed, at first we hit it off quite well. It was a challenging school and any parental interest - let alone support - was very welcome. And here was a parent who was unfailingly supportive, for a while.

Things began to change as her daughter switched off and became demotivated. Natural parental concern morphed into a search for a scapegoat, and I was a convenient target. This also served to hide the real reason for the girl’s distraction: her mother was having an affair and things at home were falling apart.

This was well-known - people talk - but no one spoke of it openly. The mother’s marital problems were damaging her daughter’s education, but I was the fall-guy.

Soon letters were winging their way to the head identifying me as the cause of the pupil’s problems; my professionalism was under attack because someone else was having an affair.

I fought my corner, but it was difficult to remain composed and during one fraught discussion with the head the red mist descended and I lost my temper. The allegations of my lack of professionalism were quickly becoming a self-fulfilling prophesy.

It was - in more ways than one - an unhappy affair. The marriage duly broke-up, the child became more and more withdrawn and my relationship with the head was little better than my relationship with the mother.

It was a miserable time. Two of us - the daughter and I, each innocent - were caught in the crossfire of a troubled marriage. I lived to fight another day, but the little girl was the real casualty.

The writer is a former primary teacher in the South East.