Georgia saw wry humour in it: the bluster and bravado of youth revolt swatted by one adult with a padlock. She also liked having the responsibility taken away: she wouldn’t get into trouble, but nobody could call her chicken when there was no way out.

Most kids were already heading inside when a trio of year-thirteen girls came screaming across well-trodden grass inside the school’s front wall.

‘It’s open at the side,’ they were shouting. ‘Everybody! We need help keeping it open.’

‘Here we go, boys and girls!’ Rolf shouted jubilantly.

A year-eight kid got so excited he tripped over himself, but Georgia, Rolf and sixty others began a charge along the grass.

While most kids made noise and hoped for the best, a group of year-thirteens had used their brains. Guessing staff would lock the front gates, they’d waited by the vehicle entrance at the side of the school.

These gates were controlled from a switch in front reception, used throughout the day by part-time staff and visitors. When the gate had opened for a busload of wet-haired year-sevens returning from swimming lessons, the girls jumped out from between two parked vans and stood in the gate’s path, activating a sensor that stopped it from closing.

Now there was a foot race. A caretaker and teacher were rushing towards the scene, demanding the year-thirteen girls let the gate close. A larger, noisier posse was belting along the front of the school grounds, trying to beat them.

Most kids at the front gate had been from upper school, but the noise and drama of the charge over the grass drew in swarms of littler kids. Georgia was a good runner and found herself near the front.

‘There is a fast train in nineteen minutes,’ a girl whose voice was not to be messed with shouted. ‘It’s on time, so if you’re coming to London, you need to move quickly.’

Maya had escaped school after she’d kicked off in assembly and there were hasty hugs as she met up with everyone outside. Tons of younger kids had piled out of the gates, but they didn’t have the bottle for a trip to London and either turned back or headed into a park that began where the school playing fields ended.

By the time they’d marched to the station, there was a core of about seventy kids, mostly years ten through to thirteen, but a few little terrors, who interrupted their walk to rob pork pies and Heineken from Tesco Metro.

There were only four ticket machines at the station. Georgia joined the queue, but was way back when the train arrived. After hesitating, she joined kids vaulting the ticket barriers and raced up steps to cross the platforms.