"When you go to the local Kumeu takeaway bar and you put the minimum wage up from $13 to $15, you're picking winners. Because some of those people will keep their jobs, some will lose their jobs."
He thrusts his finger at the hecklers who attack him for living in Parnell and hobnobbing with big business.
"You don't like business? I'll tell you what, if those half a million businesses aren't there, the 2.2 million people employed by them will be on the dole queue."
As he leaves the stage, two grey-suited diplomatic protection officers move in close. "We need to keep an eye on the lady in black," whispers one. The other slides between Key and a middle-aged woman wearing a black woollen scarf - water campaigner and independent Epsom candidate Penny Bright. Try as she might, she cannot get within question-shouting distance of the Prime Minister.
While the ministerial limos wait with motors idling in the darkness, he explains he's never actually met the owner of Kumeu Takeaways. "But there's lots of business there and they hire people on the minimum wage," he tells the Herald on Sunday.
"There's a big bank of shops up there, from pizza bars right through to takeaway bars.
"If the minimum wage goes up, the options are keep your wage bill the same and decrease your staff, increase your prices or cut your margin. And we don't think that, in the current economic environment, the last two are really feasible."
Dozens of cars are parked outside the school hall. One by one, their headlights flick on and they turn towards the motorway - most, probably, headed back to central Auckland.
"They're not local people," says Key. "Labour has never run a person that stays and does the work over three years. I don't recognise most of those people. They haven't come and seen me in my electorate office."
But he lives in Parnell - does he have any plans to move into the electorate? He replies succinctly: "No".
Next door at Whenuapai air base, the Boeing 757's engines are being warmed up. But Key climbs into the back seat of a limo and follows the other cars back down the new motorway extension to Parnell.
They say you make your own luck but really, this Prime Minister is as jammy as Devonshire tea in the West Auckland vineyards. We pay a visit to Kumeu Takeaways at lunchtime the next day. And whaddaya know: owner Jimmy Li is a Nat supporter. Yes, the 27-year-old finance graduate confirms, he pays three of his four staff just above the minimum wage. No, he would not want it to go up or he would face difficulty.
"Business is getting a little bit better but still, after tax, we don't make too much," he says.
Outside, water mains contractors Jason Ferguson and Michael King tuck into their burgers, mussels, chips and milkshakes. "I'll vote for National," says Ferguson. "Gotta be better than Helen."
Over the bridge to Huapai Main Rd and Green candidate Jeanette Elley is handing out pamphlets. It looks like she has stepped out of an older, gentler era, which is appropriate, since Huapai looks like the 70s. It sounds like the 70s. It even smells like the 70s.
Inside a hairdressing salon, a distinctive odour of fresh-permed hair lingers. An antique store stocked with kitsch tea sets beckons but there are few shoppers in today's heat and little enthusiasm for the Green pitch.
In a dairy one block over, an elderly woman chatting with the shopkeepers takes an interest in Elley. "I hadn't thought of giving the Greens my party vote," she says.
Elley confesses she lives in Mt Albert, miles outside the electorate, but the elderly woman is unfazed. "Well, John Key doesn't live in the electorate here. He never has."
Key lives in Parnell but his electorate office is just 100m away. Step inside the door and a prim, 30-something staff member emerges from nowhere, and politely ushers our reporter back out the door.
So, how often is the Prime Minister here? "As often as he can be," the secretary replies tersely.
It's fair to say that Key doesn't have a lot of time to dedicate to electorate issues - but then, look at this place. On a gorgeous spring evening, driving through the lush vineyards, it's difficult to imagine what concerns the locals might have aside from choosing whether to have sauvignon blanc or pinot gris with dinner.
Continue up State Highway 16 to Waimauku and Conservative candidate Rick Drayson is standing outside the supermarket, trying to explain his party's opposition to the Emissions Trading Scheme to anyone who will listen. Wearing a bright blue tie ("cyan," he says, "issued to all the candidates"), his opening gambit is doomed to failure. "May I have a moment of your time?" he asks, repeatedly. "Err, no," shoppers reply, grabbing their trolleys.
Drayson, 35, says he is not religious - just conservative. The party doesn't discriminate against gays, he says, though he doesn't think they should be allowed to adopt. He doesn't like abortion but can see little way of improving the law, aside from requiring that parents be consulted when a teenager seeks a termination.
He just wants to see government run in the same way he runs his family of seven: don't lie, don't break promises and don't spend money you haven't got.
Until a few years ago, Drayson was a tournament-winning war-gamer - now, he says, he is approaching the election with the same competitive determination. If you go into battle, you fight to win.
The contrast is stark in Greenhithe, where the Act candidate is going door-to-door on Archer Rayner Place, an affluent cul-de-sac where most people plan to give "two ticks to National" and aren't afraid to say so.
There barely seems any point naming Mr Act, a tall, greying businessman - he is determined to dissuade anyone from voting for him and only wants their party vote. "I'll be voting for John Key and I'm happy for you do to the same," Mr Act says.
Actually, he won't really be voting for Key. Like most of the other candidates, Mr Act lives outside the electorate. He'll give his vote to National's candidate in Northcote, Jonathan Coleman. And, okay, Mr Act's name is Nick Kearney.
Sprawling suburbia gives way to the manicured countryside of a land that seems almost too fertile for its own good. Every spare acre is cultivated. If it weren't for the drone of trucks ploughing down State Highway 16, this would be a serene slice of middle New Zealand.
Everywhere, vehicles outnumber pedestrians. This is drive-through country. There's not much for youngsters to do. Commuters and young families may love the lack of hustle - but it will eventually drive their kids away.
"The young people go away to go to university and they don't really come back till they're ready to raise a family," says Labour candidate Jeremy Greenbrook-Held, 30.
He speaks proudly of his roots out here - he knows that if you score a try in the corner at Kaukapapapa School, you end up in the ditch. But he still seems out of place. He's young. Like his fellow carpetbaggers, he doesn't live in the electorate.
Another day. A cock crows in the background, struggling to be heard above the traffic. Another evening and commuters from the big smoke churn down the highway.
Another meet-the-candidates meeting, this time at Kaukapakapa Memorial Hall, almost on the shore of the Kaipara Harbour. A board records the small community's WWI and WWII service. Dozens of names. Four members of the Honey family; five members of the Shanks family.
Key isn't at this meeting, but he's sent Te Atatu-based MP Tau Henare in his place. Greenbrook-Held is unimpressed: "For nine years, Helensville has had an absentee MP."
But Henare is gleeful. "I've always wanted to stand in for the Prime Minister and tonight I get my chance."
