This used to be part of Mr Cunliffe's electorate (not that the Herne Bay resident lived in it). In one of those odd boundary shifts, his New Lynn electorate is cut off at Titirangi, which has joined the Helensville electorate. We would be stomping through Prime Minister John Key's turf.
There was the ritual shoe-scrubbing to prevent the spread of kauri die-back disease and then we went bush, along the ridge then down the valley and into the wilds. Our boys, of similar age, streaked ahead then lagged behind.
We weren't meant to talk politics, not really, but he might be Prime Minister one day - possibly this year. I'm not passing up a chance to find out what he cares about.
His children, obviously, and delightfully as he juggles dad role with his media-in-the-vicinity persona. Not that the two are inseparable, but children have a way of disabling your defences, which isn't what you want with a journalist along.
Aside from that, he would put decency and honesty at the centre of his being (as do most politicians) but juggles the reality with the abstract.
"There's a deep problem there ... the post-modern philosophy you can deconstruct and reconstruct any idea and find a different version of some relativistic truth.
"You know what? I don't want 'relative'."
That's never going to work on the stump. As Labour knows, there's work to do.
When I interviewed Mr Cunliffe in 2008, he claimed he didn't want to be Prime Minister: "No. it's a bastard of a job and I have a young family. I don't think the two would go together." The family has grown older while his ambition has grown larger. What hasn't grown though, are his approval ratings.
"What polling is saying, basically, is that 60 to 70 per cent of New Zealanders still say they have no idea who I am. Of those who have formed a view, it's about evenly split."
Those early days of the leadership were liberating, after years of Labour trying to keep him on a choker chain. "I had the freedom to say what I really believe - that neoliberalism is a stupid idea and that we're going to change things. We're going to be a fairer, leaner, smarter, more prosperous place."
"You need an Orewa speech, don't you," I said, thinking of Don Brash's 2005 electoral springboard.
"No I don't," he says, emphatically. "I don't need an Orewa speech." I think he shuddered.
Basically, this is why we're stomping around the bush in between a morning Labour Party selection meeting and a late-afternoon function. "We do want to be able to let people know [who I am] - I'm ready to do a bit more personal stuff with the media, which is a bit unusual for me."
The bush walk idea played to his enthusiasm for the wilds. It was a good choice; the deeper we walked into the bush, the more the magic of the magnificent Waitakeres eased Mr Cunliffe off his pulpit, curbing his tendency to preach.
And it is spectacular. The track leaves a ridge and follows the river which drops sharply into a valley, creating the Fairy Falls for which the track is named. Mr Cunliffe is visibly moved by the beauty of it all with an unprompted "wow", standing in wonder at a railing as our boys race off ahead looking for gum souvenirs from the huge kauri that line the edges.
It's not a place for casual parenting, and Cunliffe jnr gets roped in as we approach the top of the largest fall. It's a classic parental balancing act - and I'm doing the same - making sure there is fun enough for living but not so much as to be fatal.
It was Cunliffe jnr who picked the spot for a cuppa and a bite. The lunch boxes opened. Isaac and I had earlier ravaged our way through a sausage sizzle at St Austell's in New Lynn, so had packed only fruit. Mr Cunliffe unbundled a tremendous spread. "Peanut butter or Nutella?," he asked Isaac. I chose peanut butter. "Made by the candidate," he announces. There were bananas, apples, a Square Meal bar and dark chocolate.
A thermos of black tea was produced. The tea was an austere offering, but there was plenty of it. There was a political analogy in what the lunchbox offered but I couldn't work out what the difference between peanut butter and Nutella might illustrate. "As always when I go in the bush, I bring enough food that no one is going to go home with less calories than they started. Going fishing is the same."
He breaks off to call his son back. Kids in the bush can be a worry. I've rounded corners before to find Isaac contemplating cliff faces and impossible descents. "I just want to be able to see you," he shouts.
At least someone was watching. Isaac took a spill - a scorching wipeout on wet rocks trying to reach a leaf in the river - with howls of pain probably still echoing through the Waitakeres. "Hey Isaac, I've got magic chocolate," said Mr Cunliffe. "I'm pretty good at piggy-back rides." He inspects the damage. "Kneecaps are the sorest."
He was decent, sincere. He's pretty good at this "dad thing", I reckon. He can look after my kids, if he's free after September.
"I'm not in this for the joyride," says Mr Cunliffe of the leadership. "It's the greatest game at one level, but it wouldn't justify it if that's all you were doing it for."
House of Cards, I say, referring to the US political drama, which is all intrigue and back-stabbing. "I'm not here for House of Cards. I have learned, defensively, some of those skills. You have to understand the dark arts to the extent you don't get burnt by them but you can't let them take over your soul, otherwise you should not be there. You don't add any value at the end.
"We've all known politicians ... who become so proficient at the dark arts that it's eaten them."
"That's no way to talk about Trevor," I say, needling him about Labour's Mr Mallard. That's when I get the Prime Ministerial look. It's kind of a glare, but mainly it's a full stop. It's pretty good, a little reminiscent of Clark's. "I wasn't thinking about anyone in particular," he says. "I'm sure there are people on both sides." I say: "Murray [McCully], then."
Mr Cunliffe: "Murray, yeah. That's a paradigm, isn't it, and that's not me."
He's no babe in the woods, though. "If you're totally naive you can't get anything done. You'd be victim to the slings and arrows of the dark arts. You have to understand it to be able to defend against it. But you can't lose your way in it either."
"What was Harry Potter's school called?," I ask. "Hogwarts," say the Cunliffes immediately, and almost in unison, with senior beating junior by half a second.
Mr Cunliffe led throughout, following the track to its end. And there we parted. And off he went, following a path far less defined, with an end far less certain.
