It was a wonkish, nervy, tepid debate, but the political earthquake had come earlier and it changes the way we look at Election 17

Timid, vague and exposed on tax, she still did enough. The morning after the first prime time TV leaders debate, Jacinda Ardern will be the happiest of the two party bosses, not because she won the debate in any signifcant sense, but simply because she didn't lose. And because of more important things that happened earlier in the evening.

The first TVNZ debate was a tepid affair, in which neither leader shone. Whereas The Nation's multi-party debate on Saturday was a zinger-full affair, driven by parties desperate for a headline, the Mike Hosking-moderated TVNZ debate was wonkish and lacking in energy. Oh, Bill English smiled gamely and looked engaged, while Ardern complemented National on the economy, consulting her on Afghanistan and even fair pay. But both spent the night explaining, not debating, and failed to explain succinctly and well. 

It was like a cup final, with the players too nervous and risk-adverse to really stretch out and play their real game. But parity will suit Ardern better; crucially she didn't look or sound of out place up there on the main stage for the first time. She wasn't completely out of her depth or any worse than English. They were both meh.

If I had come to the debate as an average voter after a hard day's work, I would have felt they were both talking at me, past me, but not to me. They were strong on vague values, policy jargon and what Grant Robertson annoyingly keeps calling 'direction of travel', but both struggled to answer the "how" questions. Sure, they want things to be better, stronger, faster, but failed to deliver to New Zealanders exactly how they would do that.

When they did delve into detail, they waffled their way into generalities. Both policy wonks, they seemed to have all the pieces swirling around in their heads, but couldn't quite get them out. English wanted to say 'trust me, I know what I'm doing'. Ardern wanted to say 'we can do better, so let's change'. Instead they waffled.

It was a series of struggles. First, Ardern struggled on tax, then English struggled on housing. English went onto struggle on wages and water, while Ardern struggled on labour reform and, oddly, even on the environment.

Perhaps most of all, English struggled to not look like a party that had been around a long time and is now drifting.

But neither convinced. When Ardern was faffing around trying to explain how she was really being "transparent" on tax because she was clear about what values she brought to the debate, English got in a line that  New Zealanders can't pay for their shopping with her values. When a viewer asked for their stance on medical cannabis, English started wombling on about proper testing for "cannabananoids" or something, while Ardern simply said yes, we'll do it.

Apart from that, the most memorable moment of the night was the first moment, when Hosking simply asked English, off the back of the One New-Colmar Brunton poll last night, "why are you losing?".

It was the first time in 12 years a National Party leader had had to answer that question and it was as devastating as the poll, released an hour earlier, had been shocking.

Because by far the most important event of the night turned out to be the poll, not the debate. Labour 43, National 41, New Zealand First 8, Greens 5, TOP and Maori Party one percent each.

Now that's a game-changer. It looks like Ardern and Labour don't need a youthquake to get ahead, enough normal, old, boring voters are getting on board. 

It gives Labour that magic elixir called momentum. It gives New Zealanders permission to get on a bandwagon. 

Polls are usually all about trends. Making too much of a single poll is usually a mug's game. But this one is different. A lead change and such a dramatic swing is something voters notice and it allows them to say in polite company that they're voting for someone new.

What few of us appreciated was just how many voters were waiting for permission to switch. And how quickly some voters would forgive Labour their flailing years. 

On a parliamentary basis, there's another key point: It gives New Zealand First the incentive to sign a deal with Ardern, not English.

Because under MMP, it's not just being ahead that helps Labour. Don't get me wrong. In a country where the party that came second has never led a government, that helps. But the key detail is how the parties can get to 61 seats, or 50 percent of the House.

On this poll, Labour and New Zealand First could govern alone. And we all know Winston Peters prefers small coalitions. National would need ACT and/or the Maori Party, and we also know Peters won't join with either. So - and it seems bizarre to say this given the 'direction of traval' just a month ago - Labour is now in the box seat. Its biggest threat now seems to be its own fumbling around on tax. An 'elegant solution' is needed.

But there's another twist in that result. New Zealand First has slipped so much that it may be losing its grip on its claim to be the 'decider'. Peters is now fighting for his life. On these numbers, New Zealand is only one seat away from a potential Labour/Greens/Maori Party government.

As a student of Helen Clark, Ardern is unlikely to want to risk the perception of such a swing to the left. But who knows? Remember, with more power comes more say. We've long thought Peters will have the most chips when it comes to coalition wheeling and dealing, but perhaps Labour will be able to insist on bringing the Greens into government alongside New Zealand First, just as Key dragged in ACT, United Future and the Maori Party. It helps to be inclusive and give yourself political cover.

First debate nerves were on display for all to see last night, and the poll made it clear why. There is so much at stake with three weeks to go. But it's now Labour with the upper hand for the first time this side of the Global Financial Crisis... and, to put it in perspective, since before Katy Perry became a star.