Simon is a ficitonal character, but his experiences are all based on reported experiences of real supply teachers in the UK

There’s a howl of animal triumph – "IT’S A SUPPPPLYYYYYY!" – as Simon rounds the corner towards the classroom with the fire escape route document in one hand and the behaviour policy in the other. After a mad dash to the school (the 8am phone call cut things pretty thin), Simon had to double-park in the car park and knows that this alone means he’ll probably never be invited back again.

He could really do with the loo but nobody’s told him where it is. The adults in the building seem to have dissolved into offices and classrooms, and the few he’s met have barely responded to his morning greeting and probably wouldn’t be able to identify him in a police line-up.

Simon has spent the past seven minutes negotiating the perplexing geography of the school. He could have sworn that he's just rushed through four identical corridors, all painted dusty-forest green... Meanwhile, Year 9 have realised that normal services have been suspended and are gravitating towards the ceiling with excitement.

Simon spent 10 years as a deputy headteacher, and is well aware that Year 9 rely more on routine and stability than any other group of humans. Behind the howls and writhing dances of triumph, he sees quieter students appraising him with febrile apprehension.

Simon stands and waits for order. He’s still "got it" – but "it" is far more difficult nowadays and far more time-consuming with students he doesn’t know. He painfully misses the relationships and the ability to walk into a room and command immediate attention from a class.

The lonely life of a supply teacher

He knows that the students need to know he’s in control. They need to know he cares, because, whether their teacher is off with a 24-hour-bug or a serious illness, Year 9 take abandonment by their teacher extremely seriously. The precarious nature of their pride and sense of identity mean that a safe classroom is essential. The balance of authority and warmth when one is a complete stranger in the form of SUPPPPLYYY is more tricky than one might imagine. 

The scrawled note of instruction for the lesson is lamentable ("exs 4-7 p.78" – but of which book?!). So Simon pulls out his bag of tricks – laminated pictures, supermarket board pens and the sparkly dinosaurs that students up to the age of 18 seem wiling to do anything for – and the lesson proceeds.

All in all, though, once they settle into a rhythm, Simon is able to drop in a few musical references and the green shoots of trust and security grow in the room. They’re a good bunch. He could face this again. If the grovelling note on his car dashboard means he’ll be forgiven…

In any case, it’s better than the school where he was informed that supply teachers didn’t have access to the staffroom, the one where the head of department sent her disruptive students to him because she wanted silence for a test. Better, too, than his early days of supply when Year 10 decided to play a complex game of animal grunts: he made the mistake of letting his frustration show, called them to account and every student swore blind their name was Ali.

Like most of the supply teachers at his agency, Simon didn’t grow up with an aspiration to become a supply teacher. To the stunned surprise of the few teachers who take the time to talk to him, he has accomplishments and talents beyond teaching that he has chosen to pursue, subsidising his mortgage and his ongoing love of the classroom with a few days’ supply teaching a month. Simon is a session musician, and the lack of marking, performance appraisal and development plans means he has the energy to get a few hours of music in on his return from a day at school.

Simon’s supply teacher colleagues include trainee architects, novelists, recognisable Casualty actors, medics and environmental researchers. His network of contacts (though he sees them less than he’d like, stopping occasionally to share a word of warning about a particularly grim school experience) has grown so far beyond the talk of schemes of learning and flight paths that he finds it hard to imagine how he spent 60-plus hours a week thinking only of teaching.

Simon lives modestly. He doesn’t have much choice, bringing home around £120 a day for his supply work, whilst the agency takes a cut he’d rather not think about. From his days as a deputy, he has a vague memory of the school paying £220 a day, but he’d rather not think about it too much... and concentrate on his music instead.

Postscript: Quality supply teachers are integral to the running of any school, because life happens and teachers are sometimes absent. Many teachers have and will do supply teaching at one point or another. The way a school treats its supply staff speaks volumes. With devastating cuts in school budgets, the fact that agencies are still capitalising on supply teachers is a scandal.

Dr Emma Kell is a secondary teacher in north-east London and author of  How to Survive in Teaching