On Friday, in the freezing pre-dawn, as wild winter rainstorms battered Auckland, Jacinda Ardern, the prime minister of New Zealand, got up to catch a plane. She was heading to Taranaki, the energy-rich province on the North Island, to defend her government’s decision to ban future offshore oil and gas exploration. Earlier in the week she had faced up to farmers about the spread of the cattle disease Mycoplasma bovis and sanctioned her transport minister, who had unlawfully used a mobile phone on a plane.

At the end of the week, weary from the ear-bashing from oil bosses and the realities of late-stage pregnancy, she headed home to the unassuming bungalow on a quiet street she shares with her partner, fishing show host Clarke Gayford.

Because it’s Friday, the cabinet papers are waiting for her, and she’ll probably work on them until about 10.30pm. “Not an abnormal day,” says Gayford. That morning at 5am they had groggily discussed what she might want to eat for dinner. What could the“first bloke” of New Zealand cook for the future mother of the nation? Meatballs, she said. So Gayford, an enthusiastic if not expert cook, is on the hunt for a tasty meatball recipe.

Less than a month away from the birth – which will make Ardern the first serving head of government since Benazir Bhutto to have a baby – Gayford, who will be a stay-at-home dad, is as ready as you can be. A room has been prepared, piles of baby “accoutrements” bought, and parenting advice has been accepted from Barack Obama (don’t panic; it’s OK to make mistakes). “How can you prepare?” he says in the thoughtfully decorated, cosy home. They’ve installed central heating since buying it a few months ago because Ardern is no fan of the cold.

Facebook Twitter Pinterest Ardern and Gayford arriving at Buckingham Palace for the Commonwealth Heads of Government dinner. Photograph: Daniel Leal-Olivas/AP

Gayford, a radio and TV broadcaster, has thicker skin. It’s less than a month since malicious rumours about his personal life reached such a fever pitch that the police issued an unprecedented statement clearing him of any wrongdoing. What was it like to be smeared?

“If I talk about it now, it just pours more petrol on it,” he says. But the instinct to watch his behaviour, already instilled by a life in the media, have been sharpened since meeting Ardern four years ago. While he’s had to rein in his enthusiasm for “a good rant on Facebook” – and has felt “like a right chump” editing his own Wikipedia page because the fake news that he was once a police cadet kept coming up in interviews – he keeps coming back to the “higher cause” of social justice and environmental action he sees Ardern getting on with.

Even so, recent weeks have been quite an eye-opener for the fishing-mad boy from sleepy Gisborne. Accompanying Ardern on a trip to Europe that took in the Commonwealth heads of government meetings, he felt right at home with the royal family: “Jacinda was given probably one of the longer audiences with Camilla and Charles.” The heir to the throne wanted to chat about fishing and advocacy groups. At dinner, Ardern exchanged notes on parenting with Prince William, while Gayford was next to “hilarious” Princess Anne.

He’s lucky that he gets to dip in and out of the “surreal” part of his partner’s job. With time to spare recently he felt the need to “reset”, so jumped in his old ute and drove to Gisborne to see a mate who “literally lives in the bush” and spent a couple of days out on the water.

It may be a while till the next reset. Ardern plans to return to work six weeks after her due date, 17 June, relieving deputy PM Winston Peters, and Gayford will be at home with the baby. “It’s going to be quite a bit different, isn’t it?” How does he function on little sleep? “I’m hoping my years of DJing will pay off.”

His parenting role models are his sisters – one who has three boys under four, the other two young girls. “I’m in their world a lot. You get a warts-and-all commentary. And my parents, of course.” His farmer father introduced him to the outdoors, fishing, surfing. He’s also had lots of stay-at-home dads coming up to him. “It’s all completely normal for them.”

At the end of the day, we’re just New Zealanders. We all know each other Clarke Gayford

He will be back working himself soon. The third season of his TV show, Fish of the Day, which travels the Pacific in search of impressive catches and a fine meal, is due to be produced next summer, though this will, of course, depend on baby. Gayford will have to be even more regimented, he accepts, and parents will have to be called on for favours. The couple will have to travel a lot, and he will probably move to Wellington for a while with the child.

Gayford made headlines again earlier this month when he posted a picture of himself on Twitter fending off a shark. Will he still be fighting off bronze whalers once the baby arrives? He’s actually quite cautious, he says, and has stopped pushing himself so much after having a blackout in the water. But there’s a plus to being next to a frightening sea creature: “It’s those moments that make you feel truly alive.”

The world will want to see the child, so how will they balance the public interest and their own privacy? They haven’t had a proper discussion yet, but he’s optimistic that interest will taper off: “At the end of the day, we’re just New Zealanders. We all know each other. Life still goes on as per normal.”

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The couple say there will be no full-time nanny, but in this green-minded household – an electric car is charging in the driveway and he hasn’t used a plastic bag this year – the question of cloth nappies or disposables is proving a tricky one. It’s hard to find reusables for newborns, he says, but they’ll do their best.

They have kept the sex of the child to themselves, though Radio NZ suggested that Clarke had said he was keen to meet “her”. What kind of child do they expect? “With each trip to your scans, where you see a little face developing, you start to think about all the projections you have on them as a person.”

Have they thought about what their child will inherit? “There’s a strong line of Gayford noses.” And temperament? He’s read how an expectant mother “should be calm and clearheaded with thoughts of bunnies and fields” as he watches his partner in robust parliamentary debate. “I’m hoping the child picks up some of mum’s temperament.”

CV

Born October 1976, Gisborne, NZ

Childhood Raised on a farm, eldest of three. Keen fisher, surfer and environmentalist

Education Palmerston North Boys’ high school. Began degree at Otago University in Dunedin before switching to New Zealand Broadcasting School in Christchurch. Pitched successful student show Cow TV to Dunedin’s Channel 9

Awards 2016 WorldFest-Houston International Film Festival: best lifestyle TV show for Fish of the Day

Family Expecting first child, due on or around 17 June

Achievements “[Jacinda] has definitely been the best thing that’s ever happened to me. I didn’t know what it meant to work hard until I started seeing what she does on a daily basis.”