By-election: A Glasgow kiss for missing Brown?

She is 49 years old, a reluctant third-choice candidate at best, and reduced to careering around the mean streets of Labour's third-safest seat in Scotland in a desperate attempt to prevent the "earthquake" that would follow if it slipped out of the party's hands.

Margaret Curran, struggling to defend her local credentials after years living away, has had to depend on the support of a cast who could turn out to be more trouble than they're worth. Her leader, whose political future might just depend on the result of the Glasgow East by-election this Thursday, is nowhere to be found.

He is a 51-year-old accountant with a developing line in unapologetic gaffes; a committed Baptist in a seat with one of the highest Roman Catholic votes in the country. John Mason is the standard-bearer of the buoyant Scottish National Party. His leader, who also happens to be Scotland's First Minister, has been at his side throughout a campaign that could generate their biggest nationwide leap forward for a generation.

Welcome to Glasgow East, one of the most deprived constituencies in the country, where up to half the residents are unemployed and the life expectancy in some parts is lower than in Gaza. After generations of complacency and neglect, for a few weeks in the summer of 2008, this sprawling collection of high-rise blocks, discount shops and boarded-up streets has become a coveted prize for the political elite of Glasgow, London and Edinburgh alike. Relying purely on evidence gathered while walking around its streets, it is difficult to work out why.

But a prize, and a crucial one, it is. At a critical juncture in his brief premiership, Gordon Brown must face a by-election in his own heartland. Victory in a seat where Labour came home with a 13,000-plus majority in 2005 would prove little; defeat could finally convince his wavering party that he had no chance of winning the next general election – at most, two years away.

David Marshall, Labour MP for the area since 1979, unleashed this electoral test late last month, when he resigned citing ill-health. Although it is still far from clear exactly what lay behind his decision, the impact is plain to see. It has been – intentionally on the part of the Government – a brief battle. But already, the put-upon residents of the constituency are showing signs of campaign fatigue.

"Don't youse be coming to my door asking me about your election!" bellowed a suddenly furious old man as he picked his way through an SNP gathering outside the Cranhill Arts Centre, pulling an exhausted-looking mongrel behind him. It is unclear whether the fierce warning was aimed at the party canvassers or the gaggle of journalists that have descended on the constituents for the duration.

Alex Salmond, SNP leader and Scotland's First Minister, arrived moments later, all back-slapping cheer and overwhelming confidence, talking to the press and pumping the hands of officials. Mr Mason followed obediently behind his leader.

Inside the tiny arts project, a group of young performers demonstrated how well they were using money confiscated from criminals and reinvested in their communities. It was stirring stuff, down to the tartan scarves and the throaty rendition of "You take the high road".

For Mr Salmond it was a symbolic performance: Glasgow's traditional working-class voters still have ambition, and they can look to the Nationalists to help them achieve their potential.

The SNP maintains that this by-election is less to do with national politics and Gordon Brown's future than the ongoing power struggle in Scotland. In the first election fought between two incumbent parties, the First Minister is keen to capitalise on his administration's continuing popularity and overturn Labour's majority. He has poured resources and people into the campaign, and visited the seat himself at least six times in barely a week.

Mr Brown has not ventured into Glasgow East. It is looking increasingly as if he is avoiding the scene of a potential disaster.

In a seat where Labour once could have put up a photograph of a candidate and won handsomely, the SNP are closing the gap, securing 14 of the 22 per cent swing required, according to the latest poll. A customarily self-satisfied Mr Salmond happily confides that his internal polling "tells me that I should keep on visiting". He is not there merely to babysit his candidate.

John Mason has already suggested that the SNP would not accept a "No" vote in a referendum on independence – "When you are asking someone to marry you, sometimes you have to persist", he says – and claimed the Labour Government is little different from Mrs Thatcher's. Despite a hysterical reaction to this from Labour, he has avoided an implosion, partly because of Salmond's presence, and partly because of a solid local reputation built up during a decade as a councillor for the area.

For Labour, Glasgow East is troubling. The constituency is a microcosm of some of its most critical social challenges, including chronic illness, with heart disease, cancer, alcoholism and obesity rates well above the national average, benefit dependency, even gangs and knife crime – and risks being seen as an emblem of its worst failures in government. Unemployment ranges from 26 per cent to 50 per cent, barely half the residents own homes, a third claim benefits and only a third of households own a car.

May Reid, negotiating the high street with a pushchair carrying two of her grandchildren, believed Labour had to remind voters of why it had dominated the area for so long: "I can't tell you what they've ever done for us. It's no fags, no booze – and no jobs at the end of it."

It has not been an easy campaign for a party with everything to lose, quite apart from the early débâcle that left Labour with a third-choice candidate in Ms Curran. The departure of front-runner George Ryan remains as mysterious as that of Mr Marshall, while the refusal of Glasgow City Council leader Steven Purcell to take his place, despite Mr Brown's urging, could have been a disaster. Labour had to bend its rules to allow Ms Curran to stand while remaining an MSP, and she has maintained that she would continue in both jobs.

Weary canvassers admit to some hostility on the doorsteps. "A few of them have taken the chance to get rid of whatever spare furniture they have by throwing it over their balconies at us," one Labour apparatchik admitted.

When the Labour bandwagon breezed into the community health shop, in Barlanark, last Thursday, it was the third time the centre had hosted visits from candidates in as many days. Mima Bell, treasurer of the health shop – a vivid example of what the community can achieve with the right help – was sanguine about the sudden attention. "They all think we're half-wits," she said of the politicians swarming over the area in recent days. "They come down at election time and a lot of them talk to us like we don't have a brain-cell between us. I don't expect we'll see a lot of them after."

As they enter the final days of campaigning, Labour remains optimistic, but wary. The real enemy, familiar to all Labour by-election operations, is the threat of a low turn-out. This might just be made worse by the fact that it falls in the middle of the Glasgow Fair trades holiday fortnight, when the city's workers traditionally take their summer holiday.

"The fortnight will be a terrible problem for them," observed George Dowd, on his way to the pub on Thursday lunchtime. "But, then again, there's not many people working around here any more."

The voters: A constituency where a hard life is the norm

Glasgow East is one of the most deprived areas in the whole of Britain. The average male life expectancy is 68, eight years behind the rest of the country. In one ward the figure drops to 58 – lower than the Gambia or the Gaza Strip. Just 7.6 per cent of its population are graduates, and almost two-thirds of households do not have a car. In some wards, half those of working age are without a job and on benefits.

The area has very few famous sons or daughters. Perhaps the best known is Michelle McManus, who rose to fame after winning the second series of 'Pop Idol' in 2003 and defied her critics by making a success as a singer, despite her size. The former footballer George Graham, who was most famous for playing for Arsenal in the 1970s and then managing the team from 1986 to 1995, also grew up in the area. He was later to become infamous as the subject of a notorious "bung" inquiry. He was fined and is now working as a football pundit. Charles Wilson, the former editor of 'The Independent', also came from the area.

Emily Dugan