It can’t have been easy being President Donald Trump’s defender-in-chief in New Zealand. But Scott Brown, the all-American, rock n’ roll US ambassador, has worn the flak for nearly four years.

There’s been controversies, incredulous interviewers, good friendships, successes and parties. He leaves on December 20 with a new guitar made from native New Zealand timber, a dream of seeing a Kiwi in space, and a tear-jerking story that has him hiding in his man cave.

Brown says he’s been blessed to be posted to New Zealand, though “initially I was a little skeptical”.

“You know, they had me down as, ‘Trump sends us a nude model’.”

Offered the job by Trump in 2017, one of the first diplomatic appointments from the new president, Brown arrived to headlines about his pin-up model days – he won Cosmopolitan magazine’s “America’s Sexiest Man” in 1982.

Brown, a former on-air contributor to the conservative TV network Fox News, says he’s enjoyed his media exposure in New Zealand, frequently appearing on the AM Show, TVNZ’s Breakfast, and The Project.

"I've really, really been impressed with the direct and fair questions, you know, and not kind of gotcha questions,” he says.

But would it be fair to say he’s been left to answer for a president that hasn’t been the most beloved in New Zealand?

"Really? Come on," he says, with a chuckle. He contends 30 per cent of Kiwis are Trump backers, and more are favourable to the president.

A rock n’ roll fanatic, Brown’s diplomacy has been conducted through music – “the great equaliser”.

Guests at his official residence, an expansive home called “Camperdown” in Lower Hutt, are immediately ushered through the formal sitting rooms into wings either side which are heaving with memorabilia – including an enormous drum kit from a KISS world tour in one corner.

The latest item in his collection: The “Unifier”.

The green Z-shaped guitar was made by a friend, Kitt, from both American oak and a salvaged native timber, of which tree he’s unsure. His official coin and pounamu (New Zealand greenstone) are embedded in the wood, which has been carved by someone from an unspecified iwi.

“We've been together one way or the other through our whaling, even before the Treaty of Waitangi. Up on Kāpiti Island, you still have remnants from whalers from my home state of Massachusetts. And then you have our first consul-general was here at the signing of the Treaty. So we've been in this relationship for almost a couple hundred years,” Brown says of the New Zealand-US relationship.

It’s a relationship he’s proud to have progressed. The “crown jewel” of his posting was the KIWI Act, a piece of US law which opened the US up to more New Zealand business people and investors.

The act was cited by Prime Minister Jacinda Ardern as an achievement of Foreign Minister Winston Peters’ farewell event earlier in the week, Brown says.

“It's something they tried for like 30 years to do, I did it in nine months. And it's a big, big deal.”

There are small achievements, such as his claim to being the only ambassador to ever meet all 120 MPs. Some, such as senior National MP Simon Bridges, he counts as personal friends.

“I made a point to knock on the door, go in their office, look in their eyes and ask them who they are, what they’re doing, what their priorities are.

“I'm a diplomat, but I'm also a person who enjoys other good people. And it's been really, really fun.”

And he’s proud to see Kiwi students head to NASA on space scholarships. The space industry is “out of control”, in a good way, and there are opportunities that he says will eventually “dwarf” dairy and agriculture.

“I envision probably in the next, between 10 and 20 years, to have a Kiwi in space. That's my dream. When I see a Kiwi in space, I'm going to crack a bottle of champagne and drink the whole thing.”

But what been most fulfilling – more than the KIWI Act – was something less political.

Brown counts himself as a survivor: The child of separated parents who took beatings at the hands of his step-father; who showed up in court at 12-years-old and through sports he changed for the better.

After a basketball tournament in Upper Hutt, he told his story to the children. The next day, a principal called saying his story resembled that of a child at their school. He was invited to again share his story.

"When I left, apparently, basically they shut the door and everyone was telling their stories and they were crying and they were emotional, and they had to basically call in counsellors ... They stopped for the rest of the day.

"If I did one thing while I'm here, that's it ... Who cares about politics, when you can actually make a difference.”

A teary-eyed Brown excuses himself, disappears into his rock n’ roll man cave, and clears his throat.