Sean moved back to the family home just north of New York and began working for a tiny winery nearby.
"It wasn't that great. We worked 10 times as hard to make a wine which was only just drinkable, so I figured if I could do that, what could I achieve if I actually had great fruit to work with?"
So a plan was hatched to eventually come back to New Zealand and make his own wine on the family vineyard, the fruit from which had been going to Peregrine Wines.
In the years following, Sean honed his winemaking skills, working vintages in Australia, the US and New Zealand and, in 2000, began a four-year viticulture and winemaking course at Adelaide University, something which, as a mature student, he really enjoyed.
"There was a group of half a dozen or so guys of a similar age in my year, and we certainly had more of a grasp of what we wanted to achieve post-study than most of the younger ones straight out of school.
"We'd get together and taste really spectacular wines which we'd bought and those informal tastings were just the most fantastic education for me."
During those student days an obsession with pinot noir began to smoulder.
Sean returned to New Zealand permanently in March 2006 with 10 years' winemaking experience under his belt, a wife and babies, and promptly began working in his parents' vineyard producing the first Brennan pinot noir at Gibbston Valley Wines and releasing it in 2007. That same year, the Brennans bought an established 4ha vineyard next door, adding elevated sites to the original block.
Sean also set about building their tiny, functionally formed winery, earth-clad barrel room, tasting room and office; all the while knowing very soon he'd be doing it all himself.
"I was completely naive and I got a hint of that when I went back to Adelaide a few years ago. I was talking to one of the wine shop guys about what I was doing and he said, 'Hang on. You're starting a new vineyard, you just had a baby, you've just gotten married, you've moved to another country, you're starting a label, are you f***ing mad!' "
So were there mornings when he'd wait in bed after his alarm clock would go off and he'd think, 'I just don't want to do this today'?
"Absolutely. After five years we're only just getting to that point when we can look out and see that (gesturing out across the green, leafy vineyard into the valley) and go 'Wow'.
"The thing that really does it for me, though, is seeing the kids run through the vines and hearing them ask, "Dad, when are the grapes going to be ready? I wanna taste some grapes!'
"When the kids show that sort of enthusiasm and you see them out playing in the vineyard with Millie, our Labrador, and the turkeys [he has a large flock of free-range turkeys], and everything feels worth it, it feels good."
4 SIPS of the week
Brennan Gibbston Pinot Noir 2009, $45
Delicious dried herbs, cranberry, dark berryfruit and plum flavours with a whoomph of succulent, yet savoury, notes, youthful tannins and a lot of life in it for the long haul. www.brennanwines.com
Wolf Blass Red Label Shiraz Grenache 2011, $9.99
This is my new favourite cheap and cheerful. I mean who doesn't love juicy, peppery, plum flavours and a spicy-sweet finish? (Reminds me of my husband after he slipped over in a batch of homemade fruit wine) but I digress. It's already scooped three gold medals in Australian shows and as soon as you sip it you'll see why. Amazing value-for-money red wine. Available in supermarkets everywhere.
Incognito Methode Traditionnelle NV, $17
Interesting breadcrust, biscuit, baked stonefruit and lemony flavours with a tangy, toasted, nutty note, healthy acidity and good, solid length on the finish. www.finewinedelivery.co.nz
Main Divide Waipara Valley Chardonnay 2011, $19
I love the way this wine smells. It's like grilled peaches drizzled with honey. There's a solid seam of acidity running through the mid-palate (meaning it's super-fresh) and you'll find tangy apricot and grapefruit flavours on the finish. It's a great-value chardonnay and, best of all, it's available everywhere. www.maindivide.com