English hit all the right notes in his speech. Farmers were already doing a lot to clean up rivers, he said. The Labour Party only discovered water quality six weeks ago, he said, to cheers. Environmental standards need not come at the expense of economic growth, he said to even louder cheers.
But the fear and frustration in the room was palpable.
"You're talking to the converted here," said one woman in the audience.
"Labour are running a real populist campaign here. They've gone and linked irrigation directly to dirty rivers.
"What's National doing to counter those simple messages and populist voting that Labour is working on at the moment?"
English was a little defensive: "I know that actually solving a problem is a bit boring these days. And knowing what you're doing is fairly uninteresting and doesn't sound uplifting.
"We are just running on reality, on the facts."
He softened his tone and tried to play counsellor.
"Don't listen too much to the extreme views, because they're not representative and you get defensive trying to deal with the accusations."
Another member of the National-friendly crowd urged English to "go on the attack" in the last 10 days of the campaign.
"If we are going to go down - and I hope we don't - we go down fighting.
"Because I can assure you, I am not going to be happy about paying a water tax."
English responded: "We will do better than that. We are going to win fighting."
The frustration continued outside the events centre, where farmer David Clark reflected on the possibility of a Labour-Greens government.
"The only way we can pay those taxes is to take that money out of the main street of Ashburton.
"We have to cut our cloth. We are just unsustainable as a business."
After his speech, English visited the picturesque Akaunui farm outside Ashburton where the owner pointed out some of his environmentally friendly drainage systems. "Don't call it a drain," former Federated Farmers president William Rolleston told him. "Urbanites will think it's some pipe putting sewage in the water."
It was an idyllic spot, nothing like the "dirty dairying" seen in environmental campaigns. A picnic was laid out on the back of a ute, and English sipped on a cup of tea as he walked alongside a man-made pool with son Bart.
The National leader said he didn't want to leave.
"If I can get through this election, I'll come and spend a day here."