For the fourth year running alcohol was banned at a school's match in New Zealand because spectators could be trusted to behave after a number of ugly incidents at previous meetings.
The grudge match between Christ's College and Christchurch Boys High in Christchurch turned from a fiercely contested rivalry into something more associated with the dark days of football hooliganism, marred by arrests and poor behaviour.
In 2009 around 250 people were estimated to have been involved in a mass brawl after the match. Police drew batons and said many spectators were "very drunk".
To counter this school authorities teamed up with the local police to try to weed out the worst excesses. Aside from a significant police presence at the match, all spectators were breathalysed and anyone found to have consumed alcohol was refused admission.
"It's pretty clear, the school don't want anyone who's been drinking to enter their school grounds," a local police officer said. "It's their right to do that."
The game passed off without incident. Christchurch Boys High won 28-3.