I sit with my pen poised above the exclusion letter and try to grace the situation with the gravity it deserves. In nine years of headship this will be my third permanent exclusion and I am reluctant to sign it, for all the new damage that it will trigger. Although my secretary is waiting to catch the post, I decide to take a few minutes to think things through again.

Sammy has been trouble since the day he arrived here in Year 8. He was trouble at his middle school, and was probably trouble even before he was born. His mother is a long-term drug addict and, although she carried him for nine months, she’s been incapable of caring for him much ever since. He lives with his grandparents, who are nice people and do what they can, but Sammy is a handful for everyone. He didn’t ask to be born, as he is fond of reminding us, and he is angry because he was.

When he was younger he bit other children, kicked them, punched them, took their toys away and broke them. As he grew older he started stealing and lying. His repertoire of bad behaviour has expanded to swearing at teachers, bullying younger students and vandalising computer equipment.

Now, at the age of 14, he is a thug, well on the way to being a full-blown sociopath.

It doesn’t really matter what he’s done this time. He’s had so many “this is your last chance” warnings and the incidents just go on and on. Sammy is well past his sell-by date and I know he’s ripe for a permanent exclusion.

His worst behaviour involves damaging people rather than things. A window can be repaired; a child’s self esteem, when Sammy’s beaten them up, is not so easy to replace. Staff struggle to maintain their dignity in their encounters with him. He always seems to hit a nerve with his criticism and he’s moved on from assaulting students to assaulting staff. The first few times allowances were made: he slipped, he was pushed. Eventually the incidents became too frequent to be “accidents”.

This exclusion will devastate his grandparents, who have attended every meeting set up to discuss Sammy’s problems during the past 18 months. They have been more supportive of the school than I could reasonably expect.

Some staff, the ones Sammy thinks are “cool”, will also be upset. They have gone the extra mile so many times it’s almost become a habit. The educational psychologist will also be disappointed. He really thought he might have the measure of Sammy, but he’s an optimist. Sammy won’t be disappointed. He learned a long time ago life is unfair and here’s the proof.

If I’m honest, I’ll be sorry too. I have stayed my hand so many times, reminded of his background. He’s escaped exclusion before, when other students wouldn’t have. I have personally devoted time and effort to getting him to behave, gratefully accepting any crumbs of compliance he has thrown my way.

But I ask myself how many times Sammy has been praised for doing a little of what most children do every day. How many students has he terrorised and how many have looked to staff for protection? Instead, they’ve seen attention that they deserve lavished on him. How many have learnt to behave a little like him in the time he has been around them? How many staff have been diminished in pupils’ eyes because of their inability to deal with him, and felt worthless because they had no strategies left?

Many staff and students will sleep a little better and come to school a mite happier for not having to encounter Sammy on a daily basis. I used to have some romantic notion that he was a loveable rogue. He isn’t.

So what will happen when I sign the letter?

Officially, Sammy won’t be able to come to school anymore, but I know that won’t stop him. With such an open, insecure school site (there’s even a public footpath running through it) Sammy will turn up here most days, whether he is allowed in or not. He won’t wait at the gate; he’ll be on the premises, in corridors and classrooms terrorising the students I am trying to protect. He’ll try to settle old scores with staff, the ones he doesn’t think are cool, rampaging through their lessons hurling abuse at them.

That’s why the fixed exclusions haven’t worked. Sammy only lives down the road. He gets bored when he’s excluded and has a kind of lovehate relationship with us. When he’s barred he wants to be here, then when he is supposed to be at school his attendance is abysmal.

Sammy has had a place at the local pupil referral unit (PRU) since the start of term. The head of year moved heaven and earth to get him a place.

She even attended the access panel meeting to plead, not necessarily his case, but ours. As a school, we all needed some respite from Sammy, and the PRU looked like the answer. In the triumph of securing a place for him we overlooked the possibility that maybe Sammy wouldn’t like the PRU. To give him his due, he did attend the first few weeks, but when he realised it was just like school, only smaller, he missed his mates and didn’t attend any more. For a while he just stayed at home, but then he decided to come back to visit us, wreaking havoc, reminding us what we’d missed.

The clock on my desk ticks. My secretary waits, but I’m still thinking.

Perhaps once Sammy’s permanently excluded he really won’t be able to return, or if he does he will be arrested for trespass. Maybe I could get an Asbo against him, although I secretly think a crossbow would be more effective. If he can’t come to school he’ll probably sit at home and smoke cannabis: his current hobby. When he needs more cash he’ll embark on a petty crime spree. Sammy has learned that adults (parents, teachers, the police) can’t touch him. All they have are words against his actions. He’s an angry young man and has no regard for other people’s possessions.

Where will Sammy be in five years’ time? If he doesn’t overdose first, he will go to prison and he’ll have caused misery to untold numbers of people on his journey there. He will be your intruder in the middle of the night, the person who snatches your mobile phone, threatens you with a knife in the street. He has no thought for others. Life’s been unkind to him and now it’s your turn.

Is there anything that can save Sammy? Perhaps a foster home or a spell in a detention centre? Maybe, when he is older and holds his own child in his arms he will begin to take responsibility for his own life as well as his child’s. Maybe fatherhood will transform Sammy, but I doubt it. At heart he is selfish and other people’s needs come far down on his list. Perhaps if the educational psychologist had another go, or if the staff just gave him one more chance? What happens if I don’t sign the letter? Don’t exclude him permanently, give it one more go?

But we’ve exhausted every avenue: Sammy has spent time in the learning support unit; has had sessions on anger management with the educational psychologist; has had a spell at the PRU; spent time in the direct alternative to exclusion room; been detained numerous times after school; his grandparents have been called in; he has been on report to his form tutor, to the head of year, to me. He has had more fixed-term exclusions than any child, been taken on outward-bound type residential trips, been assigned a learning mentor. We really have tried. The only person who hasn’t is Sammy.

I know that if I sign the permanent exclusion letter Sammy’s grandparents won’t appeal. They are grateful to the school for everything we have done to help and that makes my job harder. I try to think of the greater good.

He has cost this school so much, taken up so many people’s time. You can’t put a monetary value on the damage to the students who’ve been neglected because we have had to drop everything to deal with Sammy. The interminable meetings, the stern conversations, the endless form filling, the telephone calls: all time taken away from other children. And what about the other costs: the time spent mopping up after Sammy’s behaviour, the broken equipment, the black eyes, the distressed students and parents? There comes a time when enough is enough, and that time is now.

The school has failed, I have failed, and in doing so we have failed society. Sammy will now be society’s problem rather than the school’s. I sign the letter, liberating this school from its responsibility for Sammy and placing it firmly on society’s shoulders; your shoulders. I hope you are more successful in curbing his behaviour than we have been.

The writer is head of a mixed comprehensive in the West Midlands