THE ecstatic football-like chants of “Bowie! Bowie!” from Tory supporters as Andrew Bowie narrowly held off the SNP challenge in West Aberdeenshire and Kincardine will have grated on pro-independence ears in 2019, but if nothing else they were testament to how the SNP have breathed real life into Scottish politics over the last decade.

Bowie’s seat is one of a clear majority of Scottish constituencies that are too close to call this year, but it’s ­actually even harder to read than the SNP-Labour battleground seats in the Central Belt, because national ­opinion polls may be much less of a reliable guide to what is going on ­locally.

A traditional Tory rural heartland that even contains the royal ­family’s summer residence of Balmoral is bound to be one of the toughest ­constituencies anywhere in Scotland for the SNP to win, and on the one occasion when they did come out on top in 2015, it was notable that their vote share was around eight percentage points lower than their national average.

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They were fortunate that the Liberal Democrats, who had held the seat since 1997, were effectively still on their way down as the Tories tried to re-establish themselves as the SNP’s leading local opponents.

A residual vote of 21% for the outgoing LibDem MP Sir Robert Smith ensured that the Unionist vote in the constituency was heavily split, ­allowing the SNP to win with a bit to spare. But by 2017 the LibDem vote had ­totally collapsed, probably due to an informal arrangement to give the ­Tories a free run in exchange for the Tories returning the favour in seats like Edinburgh West.

Bowie captured the seat by a 15-point margin, and from that point on it was murderously hard to see how the SNP were going to mount a successful comeback. It was an ­extraordinary achievement when their candidate Fergus Mutch came within fewer than 1000 votes of ­pulling off the win in 2019.

That result was achieved when the SNP were 20 points ahead of the Tories nationally, and the national polls in this year’s campaign have shown a similar gap between the two parties.

The problem is, though, that the ­national gap has only remained stable due to both parties’ vote share dropping by roughly the same amount and thus cancelling each other out. There’s no inevitability that the same pattern will have been replicated ­locally.

It’s possible that the Tory vote in the constituency is predominantly anti-SNP in nature and will have remained high as the SNP dropped back. It’s also possible that the SNP may have been able to use the incentive of defeating Bowie to shore up their own support.

And a third possibility is that the Conservatives may run into trouble due to the ­informal arrangement with the LibDems breaking down. Word from the ground suggests that the Lib Dems are putting in more than their token effort, and if that leads to a greater split in the Unionist vote, the SNP’s prospects could be much brighter.

The JL Partners constituency-level projection suggests the SNP have a 32% to 24% lead over the Tories in West Aberdeenshire and Kincardine, with Labour’s vote share increasing sharply since 2019 and the LibDems holding steady. But other polling firms have pointed to radically different outcomes.

The only thing that can be said for certain is that if SNP candidate Glen Reynolds does oust Bowie, it would be a supreme highlight for the independence movement.