With barely a pause, Orla crossed the room and grabbed hold of Shannon’s wrists. Shannon, who was underweight and unused to physical confrontation, struggled to free herself, but she was no match for her tormentor, who boxed as well as danced.

Sara flew forward to prise apart Orla’s fingers, but another girl, who had so far been quiet, forced her back.

Acne Girl retrieved the foil-wrapped sandwiches from the floor and opened them up. The changing room filled with a distinctive aroma. ‘Mmmm. Smells like egg mayonnaise to me. Do you like egg mayonnaise, Shannon?’

She grabbed half of the sandwich and pressed it hard against Shannon’s closed lips. Chunks of half-mashed slippery egg slid from between the bread and down the front of Shannon’s leotard.

‘Eat up, you anorexic bitch,’ said Acne Girl.

Sara yanked herself free from the girl who was holding her back. At the same time, Shannon stamped on Orla’s toe. In her ballet tights, it wasn’t hard enough to do much damage, but it startled Orla, who loosened her grip, allowing Shannon to break free.

Shannon planted two hands against Acne Girl’s chest and shoved her. ‘Fuck off, Danielle.’

As the expletive spilled from her, the door to the changing room opened.

Mrs Carter’s intake of breath was audible in the pin-drop silence. She glanced at the floor and the collection of discarded food. Sara’s heart stuttered at the sight of her mother. From an early age, Mrs Carter had instilled in them the importance of impeccable behaviour in public and how their actions might impact on their father, a bastion of the community. Danielle burst into noisy tears while the other girls clustered around her.

Mrs Carter moved swiftly across the room and gripped Shannon’s shoulder. Tiny flames of anger burned in the woman’s eyes. ‘What on earth do you think you’re doing?’ Her words were darts of poison, pointed and corrosive.

‘It wasn’t Shannon’s fault,’ said Sara, pulling at her mother’s arm. ‘They started it.’

‘Be quiet,’ said Mrs Carter, without taking her eyes off her oldest daughter. Her gaze searched Shannon’s face, settling on the smear of mayonnaise at the corner of her mouth.

Her hand snaked out, pinching her daughter’s stomach between her fingers. To an observer, it might have looked as if she were drawing the girl into a hug. But she twisted sharply, spandex and skin, and pressed her mouth to Shannon’s ear so the others couldn’t hear.

‘Greedy little pig.’

Each word was spoken with softness – their mother never raised her voice – but enunciated as precisely as a knife-cut across the wrist.

Tears of pain and humiliation filled Shannon’s eyes, but she did not cry out. Sara heard a stifled titter from one of the watching girls. The tension in the changing room sharpened.

‘Apologize.’