We all have a colleague who inspires us. When I started working as a probationary science teacher in September 1989, it was Ian, a fellow science teacher, who was also a deputy head. He could mesmerise a class, instruct them with a gesture or a word. He was a magician, and the core of his classroom conjuring trick was that he genuinely cared about everyone he came into contact with.

I tried to imitate him. What he did effortlessly, I learned to do laboriously. After a while I got pretty good at the act and can now get “in role” by walking into school. It’s a good technique, but it’s tiring, and I have to concentrate hard with a difficult class. Then I relax and enjoy a decent class. There’s a kind of emotional balance to the day.

Ian’s commitment to teaching declined over the years, as did that of most of the senior management team as other responsibilities took over their school lives. He continued to be inspirational in the classroom, but then his health began to deteriorate and he started to take time off. He was visibly ill. Most of the staff were sympathetic and tried to support him.

About five years ago, the nature of his illnesses became less obvious. He didn’t look sick. The periods of time off became longer and more erratic.

There was less sympathy; people whispered in corners. He became an object of ridicule. He had almost a full day’s teaching on one day of the week and we used to take bets on whether he’d make it through or not. I’m now ashamed of what I did to him. The only small comfort I can take is that I didn’t instigate this persecution. I could have gone against the staffroom consensus, but I chose to be part of the in-crowd.

Some staff said he looked fine on the golf course at weekends, or that it was a disgrace he’d gone on holiday during the summer. The torture extended beyond the staffroom to the science department, where, after the timetable was drawn up, the head of department allocated groups to each member of staff. Ian was always given the worst groups. Our head of department would say: “He’s only got five lessons a week, so he can’t do too much harm.”

He’d call him “a waste of space”, or worse. We would laugh and agree smilingly to the “damage-limitation exercise”. When Ian did attend department meetings, he was made to feel unwelcome (two of us - I’m trying to drag some credit out of this - didn’t go along with this ostracism) and his contributions were rarely acknowledged.

He took early retirement two years ago for medical reasons after an extended period off sick with clinical depression. He didn’t come back to say goodbye. I can’t say I blame him. This is where I say sorry. I didn’t understand what he was going through. Sorry, Ian. Enjoy your golf.

Five years ago, I suffered a serious physical illness which meant I was absent for a term. Since then, my attendance has not been good, partly because of ill health, partly because promotion meant I had to spend more time out of school (meetings, training, and so on).

In March 2001, I was told I had a brain tumour. I’m scared of cancer. I want to watch my two children grow up; I want to grow old with my wife. As a scientist, I know the cure rate is good, excellent even. During a full year of tests, scans and more tests, I thought I was going to die. I became depressed. Recently, I was told by a psychiatrist that I suffer from manic depression (it’s now sometimes called bipolar disorder), and I’m currently recovering from a major depressive episode. Most people were understanding about the cancer; they’re less sympathetic about the depression.

I didn’t used to be sympathetic. I was cruel, dismissive of Ian. The implied message we sent was: “Why don’t you pull yourself together”; or “You look OK”; or “Come on, it can’t be that bad.”

If I had a broken leg, you’d probably help me. If I had an incurable malign cancer, you’d probably mumble something consolingly, say how brave I was and move away. If I had diabetes, you’d sympathise with the weird behaviour or sudden need for specific chemicals and avert your eyes as I injected myself. So why the discrimination?

Depression can be treated. Mine is caused by an imbalance in my neurochemistry, so I take drugs to keep it in control. But when I am depressed, my body is like a knot, every muscle fibre taut, every nerve ready to fire. Each molecule seems to weigh a kiloton. I have to plan every move. Making a cup of tea can seem like a major chore. Going shopping is a nightmare. Talking is impossible.

Twenty per cent of manic depressives kill themselves. I’ve never felt suicidal; first, because it is a selfish act and would hurt my wife and children more than me; second, at the depths of my depression, this would be too active. In a world of virtual realities, this is my virtual death.

I can now operate, using drugs, as a normal human being. But I’m not being allowed to. In July, at the end of the last academic year, I discussed the situation with my head of department, my head of house, my head. To get back into teaching, I said I needed to concentrate on the classroom. To fulfil my role as co-ordinator for gifted and talented pupils, it would be useful if I didn’t have a tutor group, so I could organise assemblies, mentor pupils, push forward this part of the Excellence in Cities initiative. If I had to have a tutor group I’d prefer not to have a Year 9 group (it’s a nightmarish year). I should also have a full day protected non-contact time to carry out my duties. They all nodded, smiled.

On the last day of term I finally received an intelligible copy of my timetable for 2002-2003. I didn’t have the non-contact time. I had a tutor group. It was Year 9.

I teach the bottom sets for science in every year group. I also teach the third-from-bottom sets (out of eight) in Years 8 and 9. Two periods a week I teach a genuinely good group. So it’s 23 lessons a week with kids out of people’s nightmares. I’m being punished. I’m a “damage-limitation exercise”. People are calling me a waste of space (behind my back, of course).

I talked to my head of department, who told me he’d “spoken to the head” and it was “under review”. I told him this timetable would make me a basket case by Christmas. He replied that you can get a lot of satisfaction from working with these groups. I agree, but not for 20-plus lessons. Every time I had a bad day I would tell him. He looked distracted, dismissive. His comments were of the “we all have bad days” sort. When I said I found the tutor group difficult, I was told I was “good with difficult groups”.

In mid-October I had a panic attack. I went to my doctor and have been off sick with depression since. I’ve had two letters and two phone calls from school - both in response to questions from me. My union helped me to make contact with the local authority’s personnel department and I have now received counselling through them.

We have a return to work after ill-health policy; this hasn’t been followed. We have a stress management policy; this hasn’t been followed.

I’m being bullied and discriminated against. I’m not a madman. I’m not dangerous to anyone but myself. I’m someone who suffers from a disability that people find difficult to understand, but is treatable. I want someone to give me back my humanity.

The writer teaches in an 11-to-16 comprehensive in the north-east. He has yet to return to school