Not everyone was excited to see Jacinda Ardern become Prime Minister. Doubts, some had a few: no business experience, no policy accomplishments, not a man. And, some of them declared, as though it quite settled the matter: how ridiculous and out of her depth would she look amongst world leaders? How ludicrous would she - and by implication, we - look?

Photo: AFP

For anyone who had seen her in action, that always seemed the most spurious of objections. She is at ease with people, all people - young, old, worldly, sheltered, grand, modest, Trump. A policy wonk, she knows the issues and dilemmas that keep world leaders from a good night's sleep. She has the kind of empathy that notices when someone has had a bad night.

So off she went, pregnant, armed with briefing papers. From the moment they touched down, it was clear that the doubters had been fretting for nothing: Macron, Merkel, May, the monarch, she clearly had their whole and delighted attention.

There was a warmth, a sense that her empathy and her positive nature was being reflected back.

Photo: Pool

Smiles and photos. Nice. Did she actually get anything? Mais oui. There was the key question of France's firm support for a free-trade agreement with the European Union. She got it. She talked international security issues with Merkel, acquired insights. She also came away with some kind of positive position on post-Brexit UK relations but really, how can you take any of that improbable house of cards seriously?

The world media was fascinated: op-eds and profiles in Le Figaro, Süddeutsche Zeitung, Le Monde. The Australian said: "The New Zealand Prime Minister has turned into a media favourite and has been getting special favours from other leaders."

Then there was a photo. A radiant photo, this leader, this young expectant mother, in a beautiful gown, and a kiwi kākahu and the whole thing was somehow ethereal and it was A Moment.

Photo: AFP PHOTO / POOL / Daniel LEAL-OLIVAS

The nation has a photo album: Dame Whina Cooper going up a gravel road, slightly stooped walking stick in one hand, a child's hand in the other; Norman Kirk taking a young Māori boy's hand walking onto Waitangi Marae. There is partnership in the images, there is inclusion, there is humanity, there is warmth. This new one goes straight to the album.

The young couple at Buckingham Palace, are formal, but they are also formal on their own comfortable terms. There is the great WW2 story about Montgomery complaining that the New Zealand troops didn't salute. Freyberg told him: yes, but if you wave, they'll wave back.

Is it just a memorable photo or is there - as some have suggested - some small subversion or revolution in any of this? Maybe. They won't be changing anything more than the guard at Buckingham Palace after this, but perhaps it reminds us that we're different here, and we like that and we want more of it, and maybe that's the kind of mood that can sustain this young leader's efforts to achieve change.

Photo: Pool

The same carping that she was inadequate for international diplomacy also expresses itself day by day here: "yes; but what's she done? It's all talk". That kind of defeatism never contemplates a beginning followed by a middle and an end some time from now.

This government has lofty carbon free goals, and of course it's much too soon to say if they'll come to fruition, but they have begun. Now let's see how many steps will follow.

Ardern spoke of the lofty carbon-free goal to students in Paris, refraining the idea that the generations before her were shaped by the debate on Vietnam, the politics of sport and apartheid, and the nuclear-free movement and that hers will be shaped by climate change.

In expressing the idea in that way she makes two key points, the first: that there can surely be no greater policy priority than this one. And the second: that when you reflect on those other large issues of history, you see that they were not simple, and progress was not easy, but they were, by then end, dealt with and the world was left better.

It was a leader's message, delivered as a leader.