'A DEAD rat on a stick would have been elected here if they'd stuck a Labour rosette on it," says engineer Alex Campbell, in the centre of his native Coatbridge. "And that's been the problem."

It is a sentiment that would have applied to a number of Labour strongholds in post-industrial Scotland, where the party's dominance has been largely unchallenged since the 1960s. But no more, if a series of opinion polls are to be believed.

Today, from Gordon Brown's Kirkcaldy fiefdom to the citadel of Glasgow and Red Clydeside, voters who once barely questioned their Labour loyalty are apparently preparing to turn their back on the party in their droves, condemning previous electoral certainties to the dustbin.

High-profile Shadow Cabinet scalps, Margaret Curran in Glasgow East and Tom Greatrex in Rutherglen and Hamilton West, are to be claimed by the Nationalists in May, Lord Ashcroft's constituency research predicts. Meanwhile, Shadow Foreign Secretary Douglas Alexander faces a humiliating defeat at the hands of 20-year-old student Mhairi Black, in an unprecedented landslide forecast to leave Labour with just a handful of Scottish MPs. Former steelworker Frank Roy in Motherwell and Wishaw, MP for the area since 1997, is another who has enjoyed huge majorities but is now tipped to lose his job.

Where has it gone wrong for a party that increased its share of the vote in Scotland at the last General Election? That the independence referendum prompted a seismic shift in the country's political landscape, with the strongest Yes vote in traditionally working-class areas, there is no doubt.

But Labour's decline has been longer than six months in the making. The current crisis can be traced back to the Iraq War, according to Scotland's leading historian Tom Devine, who believes the episode led left-wing voters to slowly start to question their political allegiances.

And the result, he believes, may well have a heavy bearing not just on the make-up of the next UK Government, but on the future of the 300-year-old Union.

"Clearly, the position is, to some extent, due to the referendum," Devine says. "The areas that voted Yes are recognised as areas of Labour loyalty. The fact that, quite openly and enthusiastically, Labour campaigned alongside the dreaded Tories has done great damage to the Labour brand. But their problems go much deeper than that. Areas of loyalty to Labour were already going towards nationalism.

"Labour have moved towards a neo-liberal position to gain votes. In that period, the SNP have moved to the left wing and stolen the electoral clothes of the Labour Party through policies like supporting the NHS with no privatisation and no tuition fees.

"In my view, there's been decades of complacency from the Labour Party and not delivering in places like Dundee, West Central Scotland and parts of Edinburgh. The referendum crystallised a feeling of alienation and accelerated it."

There are historical parallels to draw with the current predicament facing Labour, Devine says. In 1967, Winnie Ewing won a stunning by-election victory in Hamilton, widely seen as an impenetrable Labour stronghold. It remains a watershed moment in the history of the SNP, which until then had remained on the fringes. In the 1974 General Election, the party won nearly a third of the vote and 11 Scottish seats, a total that remains its high point at Westminster - for a few more weeks at least.

But Labour recovered, thanks largely to an offer of significant devolution which became its answer to nationalism and split the SNP. There was little popular support for full independence, and after the 1979 referendum failed to see a Scottish Parliament established, Labour rebuilt its support as a brilliant new generation of Scots led the fight against Thatcherism. The party of Donald Dewar, Gordon Brown, Robin Cook and John Smith was once again the party of Scotland. Tainted by the "Tartan Tories" tag after helping bring down the Callaghan Government, the SNP would win no more than three UK seats until 1997.

But the harsh reality is that there are few signs of a new influx of substantial Labour talent on the horizon, Devine argues. The Scottish giants of the left have been replaced by a "generation of mediocrity", he says, describing the appointment of Jim Murphy as Scottish Labour leader a "terrible mistake".

"Jim Murphy has been shown to be ineffective in moving the polls, largely because he belongs to a Blairite tradition that has already been rejected," he said. "The unfortunate fact for Labour is that, while their opponents have weaknesses as well, their calibre of leadership is much stronger, which is an extraordinary development.

"In the 1970s, very few people wanted independence. Now, Labour could find an attractive alternative, but it could be too late because of the independence momentum. That's going to make it much more difficult and a major factor is going to be this election.

"The primary position of the Scottish electorate since the 1980s is to ask which party will protect us best from Toryism. Labour as a UK party can do that but if they fail, I can only see another period of Tory rule and austerity, and the dynamic for independence could become unstoppable. There won't be any other defence apart from independence. If the Tories win, or go back into coalition, Labour is dead."

On the streets, there are those who insist they will be sticking with the party they have backed for generations. For many, Labour is in the blood and such bonds are not easily broken.

In Airdrie, once the territory of former party leader John Smith and a short drive from the birthplace of Keir Hardie, one of Labour's founders, Ella Mair has been represented by a Labour MP in the Commons for each day of her 74 years. She chuckles at the thought of Ed Miliband as Prime Minister and is yet to be won over by Jim Murphy. But she will not break the habit of a lifetime.

"I'll vote Labour. I've always done it, so did my family before me," she says. But she admits that there is every chance that the Nationalists will overturn the 12,408 majority in her Airdrie and Shotts constituency.

She speaks of the declining oil price as evidence of the folly of independence, but says that while one of her sons remains Labour, her two daughters are toying with the idea of shattering the family tradition by supporting the SNP. "The Yes voters are sticking with them," she explains.

In Glasgow East, one of the UK's most deprived constituencies, Natalie McGarry is apparently on course to topple Margaret Curran. She joined the SNP as a child, and counts Holyrood's presiding officer, Tricia Marwick, as an aunt. She says she deliberately took a break from political activity in her youth, making a conscious effort to question whether her allegiances had simply been inherited. Many of her would-be constituents, she believes, are now going through the same process. While her canvassing has so far backed up polling, she admits there are many undecided voters who are struggling with the previously unthinkable idea of abandoning Labour.

"You have to sometimes challenge the notion that politics are handed down from family member to family member," she says. "That's what's happening just now in seats like this. It's almost like the Labour Party has been a family for people and for some it's a very emotional thing. It's like a break-up, but they feel the Labour Party has left them, not that they've left the Labour Party. People have been having a real struggle, I think, to abandon generations of support for a party that no longer represents them like it once did."

But it appears that enough voters may already have been convinced. The bookmakers have McGarry at 1/3 to become an MP, with Curran 9/4 to hang on. The SNP candidate is using statements like that made by Shadow Work and Pensions Secretary Rachel Reeves, who recently said her party did not want to be seen to represent people on benefits or those out of work, on the doorsteps and cites it as an example of an approach that has increased feelings of alienation from Labour in her community.

"To make that statement is rejecting a huge section of UK society," she says, pointing out that many people on benefits are in work while others are jobless through no fault of their own. "It's an extraordinary thing to say and shows they're chasing the middle England vote.

"A lot of people here are angry with the Labour Party, and I'm not sure they understand the anger or know how to deal with it. The referendum is an obvious focus, but we didn't get to this position in a very short period of time.

"In 2007 [when the SNP won their first victory at Holyrood], they said 'sorry, we'll learn, obviously you want us to change'. In 2011 [after an SNP landslide at Holyrood], it was 'sorry, we'll change'. Jim Murphy comes in, and says 'we'll change'. But there's never really been any real change. In 2010, people were coming up to us and saying we don't really like the Labour Party but I'm voting for them because I don't want the Tories. I think this time that relationship has been broken."

A second round of Ashcroft polling has confirmed that the SNP surge is not confined to areas that returned a majority Yes vote last September. In East Renfrewshire, previously a Tory seat before Jim Murphy built a comfortable majority following a surprise win in 1997, less than 37 per cent voted for independence. Yet the Scottish Labour chief holds a wafer-thin lead over the Nationalists of just one point. It has been suggested that his protracted refusal to confirm he would stand in May, before eventually revealing he would be the candidate, was due to a fear that his personal popularity in the area would offer the best chance of preventing another seat turning yellow.

Back in the heart of the heartland, in Coatbridge, Chryston and Bellshill, even veteran Tom Clarke, who has represented the area since a by-election in 1982, is not safe. He recorded the largest majority of any MP in the UK less than a decade ago, and in 2010 took almost seven in 10 votes, translating to a majority of almost 20,000. But a Lord Ashcroft poll in February predicted that even this most secure of political careers was set to end in failure, putting the Nationalists ahead by three points.

The 74-year-old, who says the thought of retirement never crossed his mind when he was reselected unanimously by the constituency party, remained bullish over his chances of re-election as he prepared to board a flight from Glasgow to London for a week's business at Westminster. It is a trip he has taken regularly for more than three decades, and he is adamant there will be many more to come.

Clarke has historical comparisons of his own to draw on. He recalls that first by-election win, when pundits were predicting a strong challenge from the SDP following Roy Jenkins's famous by-election victory in Glasgow Hillhead just months earlier. The aftermath of the Falklands War added to the uncertainty. In the end, he won convincingly with 55 per cent of the vote, going on to win landslides in seven subsequent General Elections.

He questions the accuracy of the Ashcroft poll, despite the research of the Tory peer and donor being widely accepted as impartial. The statement could be used as further evidence that despite Labour being locked out of power at Holyrood since 2007, senior party figures are still refusing to accept the predicament they find themselves in.

"I've not met anybody who took part in these polls," he says. "Was this multi-millionaire Tory going to conduct a poll in a way that was going to be helpful to the Labour Party? Was he then going to publish findings that were helpful to the Labour Party? Of course he wasn't.

"There is a trend - of course there is, I'm not foolish. We took on board how people voted in the referendum and are addressing that.

"There are two elections - the one where the opinion polls and the media are saying one thing, and there's the reality I'm finding, where people are being very careful and thoughtful about what they're going to do. People are saying things like, 'Tom, we're not going to stab you in the back'.

"I'm not going to predict precise figures, but I'm convinced in my heart that we're going to get a very clear majority for Labour in seats like Coatbridge, Chryston and Bellshill.

If we allow ourselves to become dominated by polls, that could become a self-fulfilling prophecy, but I don't think that'll happen."

It was a desire to "kick out at Whitehall", according to Clarke, over poverty inflicted by Coalition policies that resulted in a narrow Yes vote in North Lanarkshire. But he insists that the prospect of another five years of Tory-led government, as well as policies such as freezing energy bills and increasing the top rate of tax, will be enough to persuade those who supported independence to return to Labour. He cites the example of Sir Charles Gray - the Labour elder statesman and former Strathclyde Regional Council leader who publicly backed a Yes vote - as evidence following a declaration that he will back Ed Miliband in May.

The voters, he says, will see through the SNP, which he brands a "right-wing organisation" which has adopted left-wing rhetoric. "We've had Labour out of office for eight years at Holyrood and five years at Westminster," he says. "Why is Labour getting the blame for all of the ills? What's going on is that the Nationalists need the Tories and the Tories need the Nationalists. The Nationalists know that a Labour government, delivering for working-class people, is the biggest impediment to independence. The Tories want to use the Nationalists to frighten English voters by saying this SNP crowd are going to run Britain. They're thriving on each other.

"It's up to Labour to get in there with the reality. That reality is the people of Scotland have had our debate about independence, they voted with a bigger majority than 10 per cent to reject it, and now we want rid of this Tory government which has inflicted so much damage on constituencies like mine."

On talk of a deal with the SNP at Westminster, he adds: "I won't have anything to do with an agreement or a coalition and I've made that clear to Ed and I know I'm not alone in doing so."

His campaign for re-election has adopted the slogan "There's barely a family that Tom Clarke hasn't helped", drawing on a the reputation he has built up over decades. On the streets of Coatbridge, voters speak highly of Clarke.

When former driver Robert McGuigan's brother was dying of motor neurone disease and the family ran up against difficulties being approved for benefits, Clarke was there to help. He passed away years ago, but McGuigan says he has never considered supporting anyone other than the "good, honest man'" who was there for him. The SNP are dismissed as "a bunch of comedians" and he says he will be voting to get rid of David Cameron, believing the country needs a Prime Minister fairer to ordinary workers. It is a sentiment that chimes with the message Labour will seek to hammer home relentlessly in the run-up to polling day.

But while a core Labour vote remains, a significant proportion are apparently no longer convinced. Taxi driver Ricky Grogan says that prior to the referendum, his passengers in North Lanarkshire weren't interested in speaking about politics, but now, it's one of the most common topics of conversation and many insist they are sticking with the SNP.

He says he knows Clarke, who he speaks of fondly, and his family. "But I think familiarity can breed contempt at times," he adds. "I think we need someone with a bit more gumption.

"For the first time in a number of generations, it will really be close here. The polls are showing a vote for Yes wasn't just a protest," he says.

But worryingly for Labour, it is not just the constitutional question that is behind the behind the SNP surge. The issues that come up - high unemployment, low wages and a cost-of-living crisis - are top of the agenda in areas where Labour candidates enjoy sizeable majorities. According to the most recent statistics, the proportion of 18 to 24-year-olds in North Lanarkshire on unemployment benefit is almost double the national average. In North Ayrshire, almost 8 per cent of young people are claiming Job Seekers' Allowance, compared to a UK rate of just over 3 per cent. Many more suffer from low pay - with one Coatbridge resident observing that supermarkets are now seen as the largest employer, replacing a once proud steel industry.

Yet Labour is no longer automatically seen as the vehicle for addressing the issues, and many voters openly question whether the party did enough for deprived communities when they had the chance. At the start of 1998, the employment rate among working-age Scots was 69.5 per cent. It reached almost 75 per cent before the financial crash, but had fallen back to 70 per cent by the time they left office in 2010.

"They've come away from socialist principles and I don't see them going back," says Joe Muir, who was raised on a council estate in Airdrie before he launched his own businesses, allowing him to buy a house in the Rushes area of the town. "The SNP are more in tune with the Scottish mentality and the way we think about welfare and jobs. I reckon quite a lot of people are going SNP, who have never voted SNP in their lives. Labour has lost any link with the local people, who don't know what they're for. It's quite sad."

On a drab Monday afternoon in Airdrie, the campaign hub of the SNP contender Neil Gray is a hive of activity, with members folding leaflets and hammering phones. The familiar Yes branding is placed alongside the SNP logo on the yellow sign of his campaign shop, a direct appeal to those who backed independence but have staunchly voted Labour in the past.

The Ashcroft poll in this constituency has indicated that Gray, a long-time lieutenant of MSP and cabinet secretary Alex Neil who took the Airdrie and Shotts Holyrood seat from Labour in 2011, is on course to win with almost half of the vote, achieving a 21 per cent swing from Labour's Pamela Nash. When she won the seat in 2010 aged 25, Nash became "the baby of the house" in the Commons.

She would have been forgiven for expecting a long parliamentary career, but now sees it in peril after just one term.

Gray says he has well over 100 volunteers at his disposal, many of them former Labour voters. Locally, SNP membership has soared from 300 to 1,100 since September, a large number of whom are former card-carrying Labour members. It is a picture repeated throughout the country. "It's going to be hard for us, we've got a lot of work to do, but the opportunity is there to win this seat," he says.

"It's been 80 years since anyone other than the Labour Party has won here and that was a Tory. That just shows the dominance that the Labour Party has had here. So many of our volunteers are ex-Labour, someone I was leafleting with in Holytown - the birthplace of Keir Hardie - worked on John Smith's campaign but has come over since the referendum.

"Our message of social justice is resonating, because the Labour Party has lost its roots in that sense. They were the original party of the working man and the working woman, but they've lost their way."

Labour strategists remain hopeful that, as the election nears, polls that have so far remained stubbornly consistent will begin to tighten as the prospect of another Tory

government hits home with its traditional voters. But, as it stands, they look likely to kick the party unceremoniously from its spiritual home.

Party chiefs accused of 'fixing' candidate ballots

WHILE the momentum has been with the SNP since the referendum, the party has faced criticism over its selection of candidates.

Calls for a "Yes Alliance", allowing one pro-independence candidate in each constituency standing under a cross-party banner, were touted by activists in the wake of the vote.

However, the proposal was scuppered by the SNP. Instead, plans were approved to allow non-party members to stand as candidates for the party. While the move was hailed as significant at the time, no non-SNP members have emerged as candidates for May's election.

Meanwhile, the party leadership has faced accusations of orchestrating the selection of favoured candidates. Membership has soared from 25,000 on the day of the referendum to reach 100,000 and, while a huge boost for the party, this has led to speculation that new members could pull the party in a different direction, threatening the interests of established power brokers.

In North Lanarkshire, two SNP councillors, Alan Beveridge and John Taggart, quit the party over the selection process in their areas. Taggart walked after a row over his failure to be selected as candidate for Motherwell and Wishaw, accusing party HQ of casting "a dark veil of secrecy over the democratic process". It is believed party officials refused to publish a voting breakdown of the ballot.

Beveridge, an ex-police officer, said he had "been alarmed by the climate of fear, intimidation and false allegations which operates within the SNP locally". It is understood that he was unhappy with the selection procedures for the Airdrie and Shotts seat. The nomination was won by Neil Gray, a long-standing employee of SNP cabinet secretary Alex Neil.

Craig Murray, a former UK ambassador, had initially been nominated in Airdrie and Shotts, but his candidacy was blocked by party bosses due to a "lack of commitment to group discipline." Following the decision, Murray said: "Those in the SNP who make a fat living out of it are terrified the energy of the Yes campaign may come to threaten their comfy position."

Insiders have complained that party rules around Gray's candidacy were breached. There have also been complaints that party office-bearers included their position on endorsements, which is not usually permitted.

Controversy also surrounded the Coatbridge, Chryston and Bellshill selection process. Dr Imtiaz Majid, a local councillor, had been included on the ballot but his candidacy was blocked and his votes redistributed. Phil Boswell, an activist from West Aberdeenshire, won the nomination. Sources claim Dr Majid would have won the race comfortably, had he not been vetoed at the last minute.

Tom Clarke, the Labour MP in the area, claimed there has been a "local backlash" by local SNP members. He said: "I have SNP members writing to me saying the person they chose is not allowed stand as candidate."