Billy was born with hearing and bowel difficulties and, as a baby, would cling to his mum. His sister was born when he was two, and Mum had to stay in hospital with her for a few days as she was ill. Billy never forgave her for leaving him. As he grew older he started to have tantrums directed at his mum; he seemed to want to hurt her even though he loved her more than anything. He became addicted to fizzy drinks, demanding up to 10 small bottles a day. He would stop talking for hours and refuse to sit and eat with the family. He threatened to kill himself and grabbed knives in the kitchen.

When Billy was in Year 4, he started refusing to come to school. Small, blond and angelic, he’d been no trouble in class. He tried hard in lessons and responded to praise - he is not clever, but was making some progress.

His mother told us he did want to come to school; he was trying to get at her and make her unhappy. We did not know the full story at that time, so we encouraged Billy with a smile and told Mum we would look after him. We never put pressure on him; if he did not want to take part in assembly, we smiled and allowed him to watch. We thought he was shy. He was manipulating us too.

When Billy was in Year 5 he began to lock himself in the toilets in the morning. Mum told his teacher about the addiction to fizzy drinks: Billy would smuggle bottles into school and take a drink secretly when he went to the toilet, which he had to do regularly because of his bowel condition, which we knew about from the start. We said he could bring only water to school. Then he started refusing to come into school at all.

We had a problem, but we didn’t have a problem. Billy was a model pupil.

Cheeky grin, friends in the playground, able to cope even though he said little. The young male teaching assistant in his class had built up a positive relationship with him. The problem was Billy’s mum and his manipulation of her.

I arranged to meet formally with her. Slowly, she told the story and how she had been given help through the hospital when Billy was small. Health visitors had tried to help with his behaviour. He had been referred to the child and adolescent mental health services but she had grown tired of doctors saying it was her fault. She hadn’t told us all of this before because she’d been advised to send Billy to special school, and she didn’t want that. She told me how he would get up in the morning and tell her to put her trainers on because when he got near to school he was going to do a runner. So she would bring him in the car. One day he brought a plastic sword with him and, as she was driving, he held the sword against her neck and said he would kill her. He had nightmares and sometimes just wanted to sit and be cuddled. At other times he would go out with older boys and get into trouble with the police. She asked for help. I asked her to trust me - I would seek advice but I would need her support to attend meetings and be honest about the state of Billy’s problems.

The school nurse came to give him a medical. He was underweight and small for his age. The nurse set up a plan to reduce the amount of cola he was drinking and she worked with his mother to improve his diet. The education welfare officer arranged to collect Billy on the days he was refusing to come to school. The family support services gave him counselling every week and the educational psychologist came to give him an assessment. The TA met Billy every morning and took him to the library to talk him through the day. The Year 6 teacher sat with him and his mother and set clear targets for his transfer to the next class. A contract was set up and he began to come into school calmly. But his mother still had to come with him.

Early in October, when Billy was in Year 6, I heard a fracas in the street from my office - shouting, pleading, swearing. I knew it would be Billy but I hadn’t had this for some time. I walked to the front door and saw Billy’s mum trying to pull him out of the car. He was kicking and holding on to the seats. I walked slowly towards them without speaking. Billy screamed:

“Leave me alone. I’m not fucking going.” I calmly told her I could not accept him into school in this state. I would call the education welfare officer, which was part of his contract, and went back inside. I saw her give one final pull and carry him into school with a look of grim determination.

She dragged him into my office. He swore and kicked the door and the walls.

I let him get it out of his system and when he finally slumped to the floor, I asked her to leave the room and spoke quietly to Billy. I was going to fetch him some water and some biscuits. I was also going to fetch him a friend to share the biscuits with. Who did he want - who would understand? Jordan, he whispered. So I left the room, quickly briefed office staff and went to fetch Jordan and biscuits, praying Billy would stay still. He did. He ate the biscuits with his friend and went normally back to the classroom.

He’d broken the requirements of his contract and, as a consequence of this extreme behaviour and in consultation with staff, his mother, the LEA and governors, I excluded him for three days. Mum was strong. She kept him in his room, where he cried and pleaded at first. Then he quietly played and read his books. When he was allowed back into school, he was told he would be excluded again if he failed to meet his targets. He has been fine since.

We had finally taken control.

The writer, who wants to remain anonymous, is head of a primary school in the Midlands