Under a cloudless sky and surrounded by the greenest of English landscapes, the two opposing forces assembled their ranks on a plot of land situated in rural Hertfordshire, like two medieval armies readying for battle.
On one side stood the scientists of Rothamsted Research (motto: where knowledge grows). On the other side stood an anti-GM movement known as Take the Flour Back (motto: cows on the grass, not cows in the grass). In between them was a not-so-thin blue line of police, who seemed to have it all under control.
Appletree field, where Britain's first trial of GM wheat is taking place, had for the moment escaped the threatened "decontamination" by the anti-GM activists who had vowed to destroy a crop they claim contains cow genes.
A band of about 200 activists was outmanoeuvred by a major security operation involving scores of police and private security guards who prevented anyone getting near Appletree field in the grounds of Rothamsted, where several small test plots of GM wheat are growing.
The local council had been given permission by the Home Secretary to impose a restriction zone around the site which allowed the police to prevent people using public footpaths leading through Rothamsted's land.
The leader of the Rothamsted experiment, Professor Maurice Maloney, said the modified wheat had an extra gene that allowed it to exude a harmless insect pheromone that deters aphids, a major wheat pest. Testing the technology in the field was the only way of judging whether it would work in real life.
"If this works, it's one way of substantially reducing the amount of pesticides used on crops," said Professor Maloney.
The scientists at Rothamsted, he said, were environmentalists at heart and took offence at being categorised as purveyors of an evil technology that harmed both humans and wildlife.
Supporters of Take the Flour Back assembled nearby to listen to anti-GM speeches. Theo Simon, an anti-GM campaigner, said: "We're here because every section of British society has rejected GM technology and this is a deliberately provocative act."
Both sides said the protest was peaceful, although two men were arrested on suspicion of public order offences.