Opinion - At the beginning of the year Jacinda Ardern would not have put money on her becoming Prime Minister.
But, against the odds, by October she achieved the unthinkable after a series of events in which three party leaders, including Labour's Andrew Little, resigned during August.
In January, though, it was a different story and then-Prime Minister Bill English would have been weighing up the threat Mr Little posed to his job. He would not have given a second thought to Jacinda Ardern.
Yet it was Ms Ardern, not Mr Little, who forced Mr English out of his ninth floor Beehive office. It was as much a surprise to her as anyone else.
"At the beginning of the year I was working on a by-election campaign. Even that came as a surprise," she said.
"To then have Mt Albert, the deputy leadership, the leadership and then this - I don't think anyone would have put up a TAB bet on that."
When Andrew Little resigned as Labour leader in early August it was too late to have his successor elected by the full party. Instead it was left up to caucus to rubberstamp Jacinda Ardern as the new leader. Some suspect Mr Little delayed his resignation long enough to ensure only MPs got to decide.
But Labour's dismal polling clearly played a part, with Mr Little saying he took responsibility for the party's falling popularity. While Labour had struggled all year in the polls it got worse at the end of July, just as the Greens got an initial boost in support after their co-leader Metiria Turei admitted lying to Work and Income while on the domestic purposes benefit in the early 1990s.
That seemed to be the last straw for Mr Little, yet, after a week of scrutiny, public sentiment turned against both Ms Turei and the Greens.
The Green Party was not helped when two of its MPs - Kennedy Graham and David Clendon - left the caucus after calling for Ms Turei to resign. She stood her ground, saying she had the support of her party and caucus. A day later she resigned.
"The scrutiny of my family has become unbearable," she said.
Ms Turei said she owed it to her family to step down to take the spotlight off them. As well, she acknowledged the controversy swirling around her was not helping the Green Party.
But she was not to be the last political casualty in August. Towards the end of the month the United Future leader, Peter Dunne, quit politics altogether when it became apparent he was unlikely to win his seat of Ōhāriu.
"I was getting a strong sense from my electorate over recent weeks once the changes in other party leaderships had occurred that there was a mood for change that wasn't there with any great certainty as recently as a month ago," Mr Dunne said.
United Future still contested the election but after another disappointing result the party then disbanded. Meanwhile, Jacinda Ardern's ascent to the Labour leadership and Metiria Turei's demise brought about a sudden shift in political prospects. Labour's support lifted in the polls, while the Greens struggled.
On election night Bill English was euphoric. National appeared to be in the strongest position to govern but the result was not clear-cut. While it had recorded a strong vote, two of its allies - United Future and the Māori Party - had been turfed out of Parliament. As well, based on how the numbers New Zealand First was in the position of determining which major party would lead the government.
Its leader Winston Peters was in no rush to start negotiating. He waited for the hundreds of thousands of special votes to be counted. Once they were, National's election night six-seat lead over the Labour-Green bloc shrank to just two. That made all the difference to Mr Peters, who agreed it would have been difficult to do a deal with Labour had nothing changed.
"When you got so close in proximity (under the election night result) and having to get a Speaker it might have been almost impossible. Nothing's impossible in politics of course. You never know but it would have made it much harder, yes," Mr Peters said.
It was ironic that it was the Greens' slump in support that helped boost Labour's vote, making the chances of a change of government all the stronger. It is unlikely Labour could have done a deal with New Zealand First and the Greens if it had won less than 30 percent in the party vote.
Meanwhile, Winston Peters said he would never have ruled out the unexpected happening, such as Jacinda Ardern becoming Prime Minister.
"We were following the polls extraordinarily closely and we knew that Labour was in emerging trouble and had been for a long time out... I didn't think ... they'd get to the level of crisis where they'd make such a decision like that in the time that they had available to them.
"But ruling it out, no, I wouldn't have because she had been made the deputy, remember, and she was polling higher than her leader. That's always dangerous for a party leader," he said.
Bill English, while disappointed, is also not surprised National is now in opposition.
"It was always possible. When I was asked earlier in the year... I said we were confident but paranoid because you never know what's going to happen.
"So we had this fascinating series of events which contributed to a change in government," he said.
The Labour-led Government is now part-way through its first 100 days, during which there have been mishaps in Parliament and criticism that some policies - medicinal cannabis for instance - are falling short of what was promised. Parliament will resume earlier than usual next year as the government tries to ensure it meets the immediate commitments it made.
There are likely to be more mishaps and more criticism but this time Jacinda Ardern will bet on being Prime Minister at the end of the year.