A haven of friendship and memories to be made, a secret garden which would be revealed to me in only a few months – that was how I viewed the school back then. Its brightly-coloured corridors, its brave stone walls, the rainbow of flowers in their cosy beds; soon, it would be mine. But for now, I could only imagine what adventures I would have in that playground when finally I could cross over the wall.

Such joyful plans as these filled my mind on that chilly Friday afternoon. I sat on the wall, my eyes darting around, picking up every sight. Standing beside me was my father, half-asleep, hands in pockets and head drooping. We were waiting for George.

Waiting for George was an unchangeable part of the routine, and it was a part I spent my entire day looking forward to. I could sit on this wall watching the school, full of excitement and energy, until it finally boiled over and out would come George, my brother and my best friend. He was peaceful, gentle, unconditionally loving; with such endearing attributes, I sometimes wondered why he had so few friends. But the thought would soon leave my mind – I never minded having all of his attention. I'd have happily waited on that wall all day for George.

A bell rang. I sat up straight, my daydreaming smile turning to a wholehearted grin. A chattering and clattering from inside mixed with the cold air, seeming to warm up the playground with an abundance of life. I focused on the doors, the light on their crystal glass windows dancing with the crowd behind it. They were flung open, and out poured what seemed to me like a million children.

George was always the last one out.

Today, as on many days, my father was pulled away by a teacher before my brother could even make his way out of his classroom. Miss Stone was her name. She scared me. Grey eyes, grey suit, grey expression – she was alien among the dazzling colours of the school. Every time Miss Stone's cool stare fixed itself on me, I whispered a silent prayer that I would never be taught by her.

"George – Problems – Office." They spoke with hushed voices, and no matter how much I strained my ears, I could only catch a few words. My father finally turned his attention back on me, crouching down to my level and telling me in a gentle voice that he was going to Miss Stone's office for a quick chat about George.

"I won't be long. You stay here and wait for your brother."

This happened often. It wasn't always Miss Stone; other teachers would come and demand a quick chat about George from time to time. Once my parents had tried to have a quick chat about George with me, to explain away problems I hadn't even noticed, inconsistencies with a so-called normal life that I'd never even come across. Their words went right over my head.

I watched as they walked over to the office, before turning my attention back to waiting for George. I didn't have to wait long. A few moments, and he shuffled out of the doors, eyes fixed on the ground, and his mind no doubt fixed on some far off world. I called his name, but he didn't respond. I jumped off the wall, intending to trot over and greet him, when the doors opened again.

It was a group of boys, George's age or slightly older, wearing their uniforms as untidily as they could manage and laughing. Their laughter wasn't like the music of the other children's laughter. It was a harsh, raucous sound that made me stop, completely still.

They were shouting. I didn't know what it was they were saying, but I could judge enough from them – their voices, their faces, their unbearable laughter – to make me want to run away and hide somewhere warm and quiet and far, far away.

George didn't even glance up. He didn't seem to hear. I wanted to warn him, to cry out and tell him to run away, but their jeers and yells were like chains fastening me to the spot. There seemed to be an army of those boys, all around the playground, shrieking and cackling, their attacked aimed not only at my brother, but at me. A lump was at my throat and silent tears were burning at my eyes. I wanted to run, but I couldn't.

One of them, a tall, lanky boy with limp hair atop a square face, bent over the flower beds I had admired so recently. My heart leapt and my whole body tensed, a spark of hope shooting up through me, and my hand gripping the wall in anticipation. A peace offering? But then my heart sank even further down, my hand turning limp and dropping to my side. No. A handful of mud.

I felt it. It hit George square in the back of the head, and I felt it too. He didn't react. He just stood there, still.

Out of the corner of my eye, I saw a grey figure. Miss Stone. She was standing by the doors, her eyes averted, but perfectly aware of the scene unfolding in front of us both. Her words were muttered and broken, but I could hear that she was trying to keep my father out of the way for just a few moments longer. Both of us stood, pretending not to watch, not even to exist. Neither of us stepped in.

As my father followed her out of the side door and into the playground, a grim look on his face, the boys scattered. I still stood there, frozen to the spot. With a mumbled goodbye, Miss Stone turned towards the car park.

"Everything alright?" my father said with a forced smile.

I could barely nod.

He went over to George and, with a weak hand on his shoulder, steered him towards the school gates. No-one said a word. My father instinctively held out his arms, an offer to lift me up onto the wall that I had so soon before loved to skip along. But now I felt no such urge. I pulled my coat tightly around me and turned away from him, falling into a weary march behind George. All I wanted was to leave.