Tony Blair's former spin doctor Alastair Campbell says Jacinda Ardern has become one of the most respected political leaders in the world.
The former UK prime minister's spokesperson, now an author, broadcaster and host of the popular podcast The Rest is Politics, has been impressed watching her leadership from afar.
He told First Up that news of her resignation came as a shock to people in the United Kingdom, where she is hugely popular.
"I go swimming every morning in the swimming pool and people there ... weren't talking about 'the New Zealand woman' or 'the New Zealand Prime Minister'. They were saying, 'What's this about Jacinda?'" he said.
"She's one of the few politicians in the world that people know her by her first name. We have one of those called Boris and he was the exact opposite to her."
At a time when politics is so polarised and ugly, Ardern had retained her dignity and impressed on the big issues, he said.
"I know that she's had a lot of criticism and pressure in the New Zealand media and particularly online stuff, but I would say Jacinda Ardern is genuinely one of the most respected political leaders in the world."
The calibre of the people paying tribute since her resignation was evidence of her high standing, he said.
"You saw some of the commentary that was coming out from leaders around the world, whether it's the Clintons, whether it's Helen Clark. Some of the big-name leaders who were really paying genuinely warm tributes to her.
"These are not people who get the wool pulled over their eyes. They recognise real quality and real political talent when they see it."
Campbell was concerned to hear about the misogynistic abuse that had been directed at Ardern, which female politicians in the UK regularly faced too.
"It's really bad and I think it's even worse for women of colour. The most-abused Member of Parliament in the UK is a Labour MP called Diane Abbott who's both a woman and Black. So I think we do have a real problem."
Campbell said a lot of the abuse appeared to be organised.
"I was briefed a while back by someone who knows about these things who said that Macron, Trudeau in Canada and Jacinda Ardern were the three most-targeted political leaders by the bot factories and the troll farms."
The strong stance that Ardern took in the wake of the 15 March terrorist attacks and during the Covid-19 pandemic could have made her a target, he said.
"As to what we need to do to counter it, I think the social media companies need to do more, but I think politicians also need to do more for each other," he said.
"And this is a battle for men as well as women. I think men have got to do a far better job at standing up for female politicians."
Campbell imagined Ardern would be feeling a mix of emotions at the moment.
"There comes a point when you suddenly realise that you used to get really, really irritated at the fact that the media were outside your door every day - and then they're not there anymore," he said.
"You look at the news and you used to be on it every night and now no one really cares what you think."
But each world leader had their own way of dealing with their new-found freedoms after leaving office.
"You have to decide what kind of life you'd like to build for yourself. You know, Tony Blair went off and made a bit of money and put that into an institute he now runs. Gordon Brown is still very reactive to political issues. George W Bush, he basically sits around painting all day, that's his big thing. So it totally depends on what the person wants to do."
Ardern would no-doubt be highly sought after by organisations keen to get her on their books.
"I have no idea what she wants to do with her future but she's ... relatively young for a politician, she's now got an extraordinary amount of experience behind her, she's very popular, she's known around the world. I mean, she's not going to be short of people wanting her to join their organisations and certainly to use her name."