There was a snapping sound and a cheer as a burly young man tore the bumper off the rear police car. At the same time, three officers from behind the barriers swooped in, snatching a slender woman who’d positioned herself with both hands on the hood of a Nissan.

More eggs and paint pounded the convoy, but a second line of riot cops moved in front of the lead cop car and started a fast march that cleared a path to the police barriers.

The crowd booed and cursed as the chunky Nissan accelerated up the ramp to the town-hall entrance. Its rear screen was cracked, and the bodywork a modern-art masterpiece of paint, eggs and flour. Long-range missiles flew over the barriers and the four councillors in the vehicle shielded behind a giant golf umbrella as they dashed towards the main entrance.

‘Scum!’ Georgia and Maya shouted, grinning at each other as the excitement drew them in.

The first councillor had just made it inside the door when a woman in a peace-symbol hoodie jumped down from a parapet over the atrium. She knocked the only female councillor to the ground, then dumped a soggy mass of custard powder and wet bread in her face.

The cops hadn’t considered attack from above. Several officers panicked and ran back from their positions along the barrier. The crowd cheered and surged forward, rattling the barriers until people at the front started feeling the pressure.

‘Back up! This is dangerous!’ someone near Georgia was shouting desperately. ‘People could get hurt.’

Up at the entrance, the hooded custard bomber had snatched one of the councillor’s high-heeled shoes, before starting a heroic sprint down the ramp towards the crowd. A chubby cop tried to tackle her, but the protestor hurdled him and the officer wound up in a heap.

There were wild cheers as the custard bomber flung the councillor’s fancy high-heeled shoe into the crowd, seconds before two large men lifted her over the barrier to safety.

Georgia looked up, grinning, as the custard bomber crowd-surfed over her head. But more bodies were moving in, and cries coming from people pressed against the barriers were getting serious.

‘Back away, back away!’ people by the barriers were shouting. ‘There are kids up here!’

There was a crash of metal. The crowd stumbled forward, carrying Georgia with it. The police barriers were designed to break before a crush became life-threatening and now more than two hundred protestors started a charge up the ramp towards the atrium.

‘No cuts, no budget!’

‘Free tuition, free school meals!’

‘Kill the pigs!’

A security guard and the three councillors who’d made it into the atrium looked about frantically, trying to lock the huge double doors. But by the time they’d spotted the floor bolts at the bottom, the protestors were too close.

Georgia paused halfway up the ramp, but Maya yanked her arm and Sam seemed high on life.