THE revving of a forklift truck being used to barricade a factory gate abruptly interrupts the silence during a serene winter's morning on the northern shore of the Fife coastline.

There's approving cheers from the morning shift workers as the truck is plonked down, blocking off vehicle access at the troubled Burntisland Fabrication (BiFab) site. One worker says: "Nothing's getting in and nothing's getting out."

The action follows febrile rumours that asset strippers had already arrived at the closure-threatened factory, which builds wind farms.

BiFab is in danger of going into administration with the loss of 1,400 jobs at yards in Fife and Lewis.

READ MORE: Nicola Sturgeon unveils BiFab rescue package

The Sunday Herald was with workers at Burntisland this week as they began what looks set to be one of Scotland's biggest industrial occupations in decades.

Burntisland's workers told us how they are ready to occupy the site until Christmas and beyond, with supplies of food, drink, and clothing already stockpiled.

There's joking and laughing as the work-in begins, but also a steely resolve to complete BiFab's current order to build wind farms, despite the workers being told they are no longer being paid.

Scaffolders, welders, painters, riggers and crane operators all spoke to me about the battle to save the company they have devoted years of their working lives to - folk like Robert Robb, a 64-year-old welder from Buckhaven.

"The young guys are terrified as they are worried about their jobs and you can see it in their faces," he says.

Despite being just a year away from retirement, Robb says he will stick out the occupation to try to save the jobs of younger workers.

"We've got a lot of young apprentices here and they don't have the contacts that us older guys have got," Robb says.

After the excitement of the blockade, some of the workers walk through a pedestrian exit towards a takeaway sandwich van that's making its daily stop outside the yard.

As the men queue for their lunch, there's nods of agreement, as Robb continues with his message of defiance.

Robb says: "The workforce in here is excellent and it's a sin that this is happening to a place like this, especially in Fife, which has got big unemployment trouble. As you can see we've got a truck against the gate and noone will get in here."

READ MORE: Nicola Sturgeon unveils BiFab rescue package

There's a palpable feeling in the air, that the workers know that they are embroiled in a high stakes battle.

Richard Hobson, a welder from Perth, is registered as disabled after losing two fingers in an industrial accident when he was 17.

Hobson fears the demise of BiFab would make it almost impossible for him to find work elsewhere.

He started to look for a new job last week, he says, but "there were maybe five jobs in Aberdeen for welders".

Hobson, who has worked for BiFab on and off for 17 years, adds: "The shipyards have closed in Scotland and contractors jobs are getting less and less. There isn't anything else."

It's the fear that the closure of BiFab could mean the end of his working life that Hobson says has stiffened his own resolve to fight back.

"I'll do this up to Christmas, if I have to," says Hobson.

Hobson says there are enough supplies to stay on site, although the plan is to run the work-in on the basis of a shift system.

Steven James, a 48-year-old veteran of the first Iraq war in the early 1990s has been a scaffolder at BiFab for a decade.

James, who lives in Burntisland, says: "It's a volatile and confusing [atmosphere] and we could be out of a job through no fault of our own."

However, like his colleagues, he's adamant that an occupation of the yard offers them the best chance of survival.

"We've got to take control and we'll be here till Christmas finishing the order," he says.

James adds: "If it goes on beyond Christmas we're ready. I know what it was like to be in a war. I was in the first Iraq war. I'm in this for the duration. I know that it's like to be in a fight."

Strikingly, there's been no resistance from the BiFab management to the work-in.

READ MORE: Nicola Sturgeon unveils BiFab rescue package

Graeme McGrogan, 28, who trains the workforce at Burntisland, says the atmosphere has remained friendly despite the crisis.

McGrogan is standing outside, dressed in short sleeves despite the biting cold weather, alongside a group of rig workers wearing BiFab orange overalls.

McGrogan, originally from the west coast, says: "I do the training here and I see how skilled and talented these guys are. I see how good the workforce is. They all want to be here and they all want to work. It's a Scottish company building Scottish windfarms - it would be shocking if we let it go bust."

Sean Mackie, 28, a rigger from Buckhaven adds: "The best thing about it is that all the guys are out together united." Then he adds: "People don't have a clue about what's coming -it's kind of like the calm before the storm."

Ryan Gabellone, 35, a rigger who's also from Buckhaven, says all the workers agree the occupation should go on until Christmas if necessary.

He says: "We're 100 per cent and everyone believes we can come through this. We don't want it to last long, but it will last as long as it takes."

Meanwhile, Liam Stewart, 44, a crane operator, feels industry in the area has been allowed to go to wrack and ruin since the Tories came to power in 2010 at a UK level.

He says: "Since David Cameron got in, this place has been going down the tubes. But I'm sticking with it and the solidarity is unanimous."

The workforce is overwhelmingly male at BiFab, but one of the public faces of the campaign to save the jobs has been Hazel Nolan - a fulltime organiser for the GMB union.

READ MORE: Nicola Sturgeon unveils BiFab rescue package

Nolan says the union's role is focussed on offering advice to the workers rather than actively supporting the work-in.

She says: "They are not just fighting for their jobs, their fighting for the whole community here and the Scottish economy. I hope it doesn't go on until Christmas - because every day that it goes on, it's a day that they don't get paid and they turned up to work on Monday and didn't get paid.

"I'd like this to be resolved tomorrow, but it will take as long as it takes."

Meanwhile, it's not clear if or when the threat to BiFab will be lifted. But for now at least, work building wind farms, that are so heavily promoted by the Scottish Government, continues along this stretch of the northern shore of the Firth of Forth ... despite the workers not being paid.