DUMBARTON is the most marginal of Holyrood's 73 constituencies, with Labour defending a vanishingly small majority of just 109 over the SNP. 

But while that number is a golden opportunity for a Nationalist gain, it is also a mark of the tenacity of incumbent Jackie Baillie.

Scottish Labour’s deputy leader is the only one of her party’s MSPs to have occupied the same seat (with boundary changes) since 1999, and one of only three MSPs standing for re-election to do so, the others being the SNP’s John Swinney and Fergus Ewing. 

She has a formidable record for holding on, and a local profile to match.

She has also been lucky in her opponents - never facing the same one twice. 

This time she’s up against the SNP’s Toni Giugliano, a mental health charity worker who has tried to become an MSP and MP in Edinburgh, and who Labour are keen to label a carpetbagger.

“On paper, they should win this,” admits Ms Baillie.

“But I’m an old diehard campaigner, and I am pounding every single street I can find and talking to every voter I can find to make a difference.” 

The seat combines parts of West Dunbartonshire and Argyll & Bute councils. 

The former, which voted Yes in 2014, brings in Dumbarton, Bellsmyre, Renton, Alexandria and Balloch. The latter takes in well-heeled Helensburgh and the western shore of Loch Lomond all the way north on the busy A82 to Ardlui, past Tarbet and Arrochar.

Crucially, the western side also includes Garelochhead and the Trident nuclear submarine base at Faslane.

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The campaign is dominated by what independence would mean for the base and about services at Alexandria's Vale of Leven Hospital.

According to Mr Giugliano, the base would become home to a post-Trident Scottish defence force without a significant impact on jobs.

According to Ms Baillie, who has bucked her own party’s disarmament policy, independence would mean Trident’s removal and put thousands of well-paid salaries at risk. 

The hospital debate is even more polarised. 

The SNP point out the Vale lost its A&E almost 20 years ago under a Labour-led coalition in which Ms Baillie was a minister, and say that when Ms Sturgeon was later health secretary, the hospital was stabilised and more services added.

While Labour argue the Vale has suffered 14 years of creeping cuts and threats under the SNP, and that services have been taken away since Ms Sturgeon reviewed it.

“I don't much care which government is in control - if they are attacking the Vale of Leven hospital, I will defend it with my dying breath," said Ms Baillie.

“The one thing people know locally is that I always stand and fight for their interests.”

Ms Baillie won’t predict the result, but says the reception on the doorstep is far better than in 2016, when there was open hostility in the wake of the independence referendum

“It's much warmer now. People want to have conversations on the doorstep. And even if they're not voting for you, they're not slamming the door in your face," she said. 

“There's a really positive vibe out there. They're prepared to give Labour a hearing, and Anas Sarwar has contributed to that. People like him.”

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However a confident Mr Giugliano, who has a knack of steering everything back to Ms Sturgeon’s “strong leadership”, detects little enthusiasm for Labour.

He said: “I find it staggering that Labour present the hospital as something they care about, because they downgraded it and removed the A&E when Jackie Ballie was a government minister.

"She’s been very good at twisting the truth on this. There are 15 services that have come to the Vale [under the SNP]. If the hospital was in any shape or form vulnerable, we wouldn’t be adding services to it.”

Her “constant scare-mongering” only demoralises the staff, he adds.

As for Faslane, and whether voters will prefer real jobs today to speculative ones tomorrow, he says: “It’s about putting forward an alternative vision for Faslane.

"What  she’s saying is that Faslane can only thrive if we have nuclear weapons. Naval bases across Europe function quite successfully without nuclear weapons.

"This idea that you have to have nuclear weapons for a naval base to be successful doesn’t add up.

“My message to local people who work on the base is very clear - your talent needs to be retained.

"An independent Scotland's defence capabilities need to go beyond Trident. That means ensuring that we have a variety of defence capabilities, and not just Trident.”

READ MORE: Holyrood's bloodiest fight - Edinburgh Central

It’s been a bruising fight.

“When people lack a vision and a record, they go personal on you, and that’s what I’ve had from Labour.

"I’ve had a lot of personal attacks. I’ve had a lot of people questioning my professional work. They have just gone really low and personal," he said. 

“At the end of the day, people vote for parties and vision and ideas. People in Dumbarton want change.”