Good supply teachers are becoming of paramount importance to keep educational systems going as teachers experience higher stress levels and take extended periods of absence. So why, then, are they often regarded as somehow lesser teachers than the permanent staff in the school?

I recently moved back home to Scotland, having taught for many years in England. I had ended up as head of the English faculty in a secondary of 1,600 pupils. The department was thriving and successful and in the most recent Ofsted inspection I was judged to be an “excellent” teacher and the faculty was judged to be “well led”.

Although I had always enjoyed my job, I really had no intention of doing any more teaching. I looked forward to a complete career change. I wanted to live in a rural idyll and write. And so I did, until the local secondary school asked me to help out.

They had an English teacher taking four months’ leave and no English specialist available to fill in. I happily agreed, thinking it would give me an introduction to a new educational scene, allow me to meet with local professionals and supply me with some very welcome money. What I did not realise was how harrowing the whole experience was going to be.

As a teacher I was a helpless inadequate in the first few days. I was exactly the type of teacher of whom, previously, I had been contemptuous.

The ineffectual supply teacher who nags and shouts at classes had always had my censure. I am not talking about difficult classes - those we all dread - full of unmotivated and disillusioned students who delight in disrupting and diverting. I watched pleasant, motivated students turn into kids from hell when they had a supply teacher, and I had always blamed the teacher. Many of them never came back and I never wondered why.

Well, I know now. I walked into my classes with the confidence of the innocent and immediately hit the wall of “Great, a supply teacher”. As the days went on, I began to recognise the sparkle of glee in the eyes of the students when they saw a stranger at the front of the room.

One boy, seeing that I was not his usual teacher, made a beeline for a cupboard and swept all the folders in it on to the floor, to the delight of his classmates. Other problems involved changing seats, names, claiming to have already done the work set and so on.

These are all very familiar to any teacher who has ever covered for another. The difference with the supply teacher is that she has no reputation in the school. She desperately needs the support of the school’s disciplinary structure.

It took me weeks to attain quiet, hardworking classes and that was in no small way due to the help of a very supportive department who believed me when I said that, actually, I could teach, that, in fact, I was once quite good at it.

There were times, in the dark watches of the night, when I found that difficult to believe myself. Many an evening I tried to convince myself that it wasn’t worth the educational contacts or the meeting with professionals or, indeed, the money. Pride, however, prevailed.

Gradually things began to improve. Towards the end of my temporary posting, I even had the courage to tell students to take their coats off in the corridor without fear of being, at best, ignored. That felt like a major achievement.

In the course of all this, I learned a great deal and came in contact with many supply teachers who will never go into schools again. This is a desperate waste of talented, highly qualified professionals who would rather drive taxis than enter a classroom.

Imagine a situation where we could not staff doctors’ surgeries because locums were regarded as less qualified by staff and patients alike. The idea is ludicrous. If schools don’t want the supply system to disintegrate completely, we must, first of all, change attitudes.

When, after many weeks, I reached the stage of actually having conversations with my classes, one of the most frequently asked questions was how I was going to manage with not having a job when the permanent teacher came back. I explained carefully that I had come in to help out, not to make a career of teaching in their school.

Pupils must be made aware of this, that the supply teacher is a valuable commodity that schools cannot not do without, not some burnt out case who is desperate for the money. This message must be understood by staff, too.

Any misbehaviour of pupils who have a supply teacher, or indeed a new teacher, should carry instant sanctions. Sanctions must be instant as the supply teacher may only be in the school for a short while; they must be well publicised and the reasons for them highlighted to pupils, staff and parents. In other words, the supply teacher must be regarded as a visiting expert and be treated as such. The school discipline policy should incorporate specifically the special position of supply teachers.

I have been back to the school. I have made new friends and have enjoyed learning new systems of education after so long in one school. I was lucky.

I was somewhere which understood that supply teaching can be a nightmare.

However, I do not intend offering my services to any other school, not until, at least, attitudes towards supply teachers change.

Jennifer Baker is freelance writer and occasional teacher