National made many specific mistakes of course, but arrogance is the thread running through all of them:
(1) There would not have been a Northland by election without National’s arrogance. They put Sabin forward in the 2014 general election knowing that there were “rumours” hanging over him that could force him to later resign. They let that happen because they were distracted by other matters at the time, and because they assumed that later winning a by election in the safe seat was a foregone conclusion.
(2) They underestimated Winston Peters and his Northland roots. Key wrote him off as having “zero” chance, a mistake that probably crystalised the protest vote support for Peters in that first shock poll. That quotable misjudgement haunted the whole National campaign.
(3) They never acknowledged that the circumstances of the by election were their fault, and they never apologised to Northland for it. An apology would have done much to quell the power of the rumours.
(4) They selected a weak candidate with an inquiry hanging over him.
(5) They selected their candidate too late, and started their campaign too late.
(6) Their campaign was (according to Farrar) organised and run by a Wellington team, putting off the locals.
(7) They never let their candidate be himself and speak for himself. Refusing to put him in the studio with Peters (and having Joyce “managing” him from off camera during the debate) completely undermined his credibility.
(8) They lied about the number of jobs created in Northland. It was never plausible, they got caught out, another indication of treating the locals with contempt.
(9) After the polls putting Peters ahead they panicked. That panic took many forms, the first was to promise far too much pork far too soon. It was just too obvious, and they were ridiculed for it.
(10) They threatened locals to keep quiet until after the election. That’s a terrible, terrible, terrible look.
(11) They flooded the electorate with Wellington suits and limos. By now it was too late, and this just further emphasised the panic and the disconnect with Northland.
(12) They depended too much on the “Key magic”. That is now a busted flush.
At every level these are mistakes born of arrogance – the sure and certain knowledge that they could take the voters of Northland for granted, and (as things started to go wrong) that the clique around Key knew best. On top of decades of neglect it was too much. And so to many people’s surprise (including mine!) pride went before a fall in Northland.