GIVEN that Mhairi Black retained Paisley and Renfrewshire South for the SNP in 2019 with an absolute majority of the votes cast, it’s intuitively hard to believe that the seat could be in any danger of falling to Labour this time.

But nevertheless that’s the position, not least because Black herself will not be standing, having retired as an MP at the age of just 29 after wearying of what she describes as the “toxic” culture in the House of Commons.

The first concern for her party will be how much of the 50.2% vote share she took five years ago came from people won over by her unique personal appeal, and how much came from those who would have voted for the SNP regardless of candidate.

The vast majority will almost certainly have been in the latter category, but nevertheless even if Black’s personal vote accounted for only 2% or 3%, that could be enough to make it significantly more difficult for the SNP to defend the seat with their new standard-bearer Jacqueline Cameron, who is a local councillor in Johnstone and also the depute leader of Renfrewshire Council, but is nowhere near as well known to the public as Black.

A second issue is that boundary changes, which bring Linwood into the constituency but see other territory lost, have the net effect of reducing the SNP’s advantage over Labour from 2019, albeit only slightly.

On a uniform swing, Labour would now gain the seat even if they are two points behind the SNP nationally – with polls suggesting they are probably doing somewhat better than that.

And as in the other Paisley and Renfrewshire constituency to the north, the unionist vote was heavily split last time, with notional figures suggesting Labour took 25% of the vote within the new boundaries and the Tories took 18%.

READ MORE: Gavin Newlands faces fight for seat in Paisley and Renfrewshire North

If there is dramatically greater unionist unity behind Labour on Thursday, the SNP could struggle to cope with that given that their own vote share is likely to be significantly reduced.

The pollsters’ constituency projections suggest the SNP’s current local position is challenging but not unrecoverable. Find Out Now have them trailing Labour in Paisley and Renfrewshire South by 42% to 34%, while JL Partners have the race a smidgeon tighter, with Labour ahead by 40% to 35%.

One thing is for sure: the SNP will spare no effort in trying to close that modest gap, because they will be fully aware of the symbolic significance that is likely to be attributed to a Labour gain in Black’s old seat.

Douglas Alexander’s uncomfortable body language as he conceded defeat to Black in 2015 became one of the defining images of that year’s SNP landslide, and the media love nothing better than being able to show that an iconic election moment from the past has been turned upside down.

Labour have selected the high-profile and controversial Johanna Baxter, former chair of their National Executive Committee, to be the potential beaming face in a thousand newspaper photographs on Friday morning. The SNP still have a reasonable chance of spoiling that party.