I had been teaching at the same school for almost 20 years. No job is 100 per cent enjoyable - teaching brings out the best and worst of times, usually within the same hour - but the good vastly outweighed the bad.

As well as teaching chemistry, I was a sixth-form tutor but was also involved in music. I founded and ran the school’s big band, which had 12 to 20 members at any one time, and recorded and performed regularly.

Then the school started to talk about having to trim costs. This September, the Year 9 intake fell by about 50 pupils, and sixth-form numbers dropped. Next year, it’s expected to be even worse. Budget cuts just compounded the problem.

The school pared down, but most of the budget was tied up with staff salaries. I was told I was at risk of redundancy. Those in the redundancy pool had to write a list of what we had done in the classroom over the past five years.

I felt the system discriminated against me. A previous head said a contribution to extra-curricular activities was a must, but the new head said this was irrelevant. I had mostly taught chemistry and was required to teach A-level whereas others in my department had done more across the curriculum, such as the odd period of maths. It was suggested that my profile was too narrow.

One day I walked into the staffroom and you could have cut the air with a knife. I jokingly said, “So who’s it going to be?” and there was this deathly silence.

My head of department told me it did not look good. It came down to me and a colleague, and the senior managers said they could not choose between us. They asked us to attend a competency interview which would examine our views on e-learning and Assessment for Learning.

I had started teaching in 1989 and felt out of touch. My younger colleague would be much more au fait with these things. I didn’t fancy my chances.

I felt at a disadvantage and refused to take part. When told I had no choice, I went off with stress. Before that, I had only taken about 25 days off in 20 years.

In the end, they drew our names out of a hat. I couldn’t believe my career could be halted so randomly and unreasonably. I thought it would be resolved with at least a nod to professionalism, but my fate would be decided by an act of chance.

It was like some cheesy raffle, witnessed by the head and union and local authority representatives. The head rang me afterwards and said: “It’s you.”

It was absurd. I was 46, had four kids, a mortgage to pay and was being thrown out of my job because my name came out of a hat. It was like jumping off a cliff.

I went to a solicitor, who picked their argument to pieces. The school found me a secondment at a nearby school, covering a teacher on maternity leave for a year. I was in no position to refuse.

But I’m still angry. The local authority knew about falling rolls 13 years ago but did no financial planning for it.

I’m entitled to go back to my old job next September - if it still exists - but more job cuts are likely. This time, only the head’s job is safe.

If I do go back, I’ll be damned if I’m going to take up extra-curricular activities. I relished those roles and gave a huge amount of time to them, but I have to save my own bacon. They no longer carry enough weight.

It’s not what I went into teaching for, but I have to be practical. The head said he could not change the system, but I expected him to resist this type of arbitrary financial decision. I wanted him to show some backbone. After 20 years’ service, I thought I was entitled to that much.

As told to Hannah Frankel. If you have an experience to share, email features@tes.co.uk.