Student List cleaned up at Serbia’s parliamentary elections. So it was only fitting that the morning after a night of raucous celebrations, the movement’s supporters were gathering, bin bags in hand, at Pioneers Park, opposite the national assembly building in Belgrade.

For the previous 18 months, this small patch of greenery – with its established trees and playground – had been a no-go zone. A pro-government camp known as Ćaciland had taken over the space with convicted criminals living there in white tents, happy to attack journalists, or anyone else who came too close. Police stood by but did nothing to prevent the violence.

On election night, it seemed that thuggery might be on the cards again. Half an hour before the polls closed, large numbers of masked, black-clad men started gathering in and around Pioneers Park.…