National had promised it would flex its muscle as a large Opposition party, but Labour probably wasn't expecting it to happen quite so soon - or quite so audaciously.
It came seconds after the MPs were sworn in - a ceremony replete with bonhomie and bipartisan good spirits.
But Shadow Leader of the House Simon Bridges had been quietly counting as the MPs went up and found the government parties wanting. They were at least five short with NZ First leader Winston Peters and Trade Minister David Parker on the way to Apec as well as two other Labour MPs and a Green MP away.
Just as the vote to elect Trevor Mallard as Speaker was to be held, Bridges asked if MPs who were not yet sworn in could vote.
Panic ensued. Bridges strode around with his most Very Serious Face on. There were mutterings about National putting Anne Tolley up for Speaker rather than letting Mallard get it uncontested - just as Labour had done with Mallard when David Carter was elected Speaker back in 2008. Only National might have actually succeeded.
Gerry Brownlee - a former leader of the House - observed they could go ahead with the vote "it just might not be the result you're expecting".
Mallard's face turned grey.
There were hushed consultations with Leader of the House Chris Hipkins. Hipkins scurried from Bridges and Gerry Brownlee to Prime Minister Jacinda Ardern's desk. There was a lengthy huddle and he scurried back to Bridges, Brownlee and National Whip Jami-Lee Ross.
English sat impassively and National's deputy leader Paula Bennett rose to get a glass of water, a serene smile on her face.
Then came a round of handshakes. Some red returned to Mallard's face. There was clapping. The vote was put. Mallard was elected unopposed, and thanked the MPs for their "delayed confidence".
Afterwards it emerged National had used their knuckle duster powers to cut a deal on the floor of the House - using their power to force Labour into a backdown on the number of select committee places for MPs.
Labour had planned to allow 96 places for MPs on the select committees that scrutinise the legislation before Parliament. That would have meant about seven National MPs had no place. National had wanted - and got - at least 108.
As it later transpired, National was one down as well with David Carter away and Labour could have won the vote - it had 58 to the Opposition's 56. It had been a brazen bluff.
Even had Tolley won, it could have been rectified by a later vote of no confidence in her.
But that would have been very messy indeed and not a good start for a new government - or a new Speaker.
National will not get the same opportunity again - the rules of Parliament allow for a proportion of MPs to have their votes cast when they are away.
The scenes of the Opposition holding the Government to ransom on day one were, as English later said, "unprecedented".
There are procedural hiccups for all new Governments - but rarely on the scale of the Opposition being on the verge of bringing down the Government.
Given National had already publicly said it would vote for Mallard as Speaker, it was also white-knuckle audacious. It bordered on political blackmail.
It earned an unrepetant Bridges the first 'death stare' from Ardern for spoiling her day.
When she stood to congratulate Mallard, she pinioned Bridges with a glare as she spoke about the need for Parliament to serve in the best interests of all New Zealanders: "You will see this side of the House maintain that spirit in the way that we work inside this House and I hope it is a spirit you will see maintained by the Opposition."
In the long run, it may well have saved Labour future grief, as Bridges later pointed out.
National was determined to stick its heels in over the select committee roles, including forcing prolonged debates on the matter in Parliament. That would have eaten into Labour's 100 Days programme.
But in terms of future intentions, National could not have made itself clearer. It made the Government look like fools. It was not joking when it said it would make the new Government's life hell.