A CONSENSUS seems to be emerging that Holyrood 2016 has been the electoral equivalent of watching paint dry. I'd agree the campaigns have been lacklustre but that doesn't mean it's been a boring election.

Of Holyrood's main parties, Labour, the Liberal Democrats and the Greens have produced bold - their opponents would say reckless - proposals to use the parliament's new powers to increase income tax in order to challenge the UK Government's austerity agenda and protect threatened public services.

We shouldn't underestimate the significance of that in the story of devolution.

Even before the referendum, all the pro-UK parties recognised an appetite for a more powerful Holyrood.

That was realised with the new Scotland Act and now voters have a serious choice: are they willing to pay more for improvements in education, health, transport and all their other services run from Edinburgh?

Interestingly, their answer seems to be "No".

Labour is struggling to avoid coming third in a national election for the first time in more than a century. The LibDems have sunk without trace. The only party thriving on a pledge to increase income tax is the Greens, who are on course to win a record number of seats next week.

Patrick Harvie's party has another selling point, of course, which goes a long way towards explaining things. It supports independence.

If this elections has told us anything, it's that the Scotland Act hasn't had the desired effect, not yet at least.

For all the high falutin' talk, all that 'recognising an appetite for more powers,' there were some pretty naked political calculations behind the bill.

The pro-UK parties wanted to put the SNP on the spot and drag the debate away from the constitution and towards a traditional right-versus-left agenda.

Under that scenario, and accepting the received wisdom that Scotland leans predominantly to the left, you would expect Labour and the LibDems to be doing rather better than they are. Yet the SNP, offering a modest tax cut of £177 to higher rate income tax payers next year, is riding high at more than 50 per cent in the polls.

That it can count next week on the support of 90 per cent of Scots who voted Yes in the independence referendum says it all. The constitution is still king in Scottish politics.

The Tories have understood this. For all her talk of politics "moving on" after the Scotland Act, Ruth Davidson has majored not on her party's low tax plans but its resolute opposition to independence. Labour, trying to win back 'soft Yes' voters without slaughtering the choice they made two years ago, has been left stranded.

There are other factors, too, not least the extraordinary personal appeal of Nicola Sturgeon, the stand-out candidate for First Minister. And then there is the Scottish Labour brand, which the SNP has trashed energetically since coming to power a decade ago. With more than a little help from Labour itself.

But it is the deep, seismic constitutional faultline that continues to dominate. What else can explain the heap of contradictory polling data that have emerged in the past week?

SNP supporters, concluded researchers at Strathclyde University, were more left-wing than Labour voters. So why don't they switch to Labour or the LibDems and the promise of progressive tax rises to protect public services? It's not hard to figure that one out.

A separate poll, conducted by Survation for the online grassroots campaign organisation 38 Degrees, found 71 per cent of people agreed that "politicians should blame Westminster less" as a result of Holyrood's new powers.

A big majority, in other words, agrees with the pro-UK parties that have been saying that about the Scotland Act for months. But, so far, their entreaties have been to no avail in terms of prising support from the "Westmonster"-bashing Nationalists.

Ms Sturgeon will win at a canter next Thursday and earn her own mandate to be first minister. A new cabinet will be appointed reflecting her key manifesto commitments to reduce the attainment gap between rich and poor school pupils, deliver increased free childcare and reorganise the NHS.

But the big questions for her government over the next five years will still be these: How will it frame a new case for independence? How will it built support? Will it seek a second referendum?