So we find ourselves at polling day in Glasgow East. The sun is beating down upon us in one of the finest days of the Scottish summer. What will this mean for turnout - and the SNP's chances of delivering that much-promised political earthquake?

Common sense tells us that people are more likely to wander down to the polling station when the weather is good than when the weather's bad. Nobody wants an unnecessary drenching.

We already know that many constituents are on holiday. But are those left behind more likely to vote Labour than SNP - or to vote at all? It also seems incongruous to be placing so much emphasis on the absences caused by the Glasgow Fair holidays in a constituency we are told is among the UK's most deprived.

Having spent two weeks on the campaign trail, that is true in parts. There are pockets of the East End that bring a sharp intake of breath. Yesterday the SNP campaign concluded with a press conference in Wellhouse Crescent, off the Edinburgh Road.

It was as grim a road as I have witnessed, not just in Glasgow but anywhere in the UK. Block upon block of old-style semi-detached "cooncil hoose" had a steel grid for windows and a steel plate for a front door.

The previous day two kindly activists took me on a tour of their part of Easterhouse. On one side of the road were well-manicured Barratt homes. On the other was pebble-dashed local authority flats, which have been standing for 50 years and which last underwent refurbishment 20 years ago. Glasgow Housing Association, which gained control of them several years ago following a "stock transfer" - ie privatisation - from Glasgow City Council, sees them as "core" stock for the future. The activists and residents want them demolished.

From first appearance, they did not scream poverty - or Gaza Strip. But I was told the reality for those living there was having to share two bedrooms and a tiny bathroom and kitchen between two adults and often four, five or six kids. Families are big in the East End. The boys would have one room, the girls another. The parents would sleep in the living room.

And out of their window each evening they would see gang fights on the open piece of land beside the derelict school. The assailants were at times as young as eight or nine. Fourteen-year-olds would raise their T-shirts to display their scars of battle. They were inevitably fuelled by Buckie - Buckfast fortified wine - or some other potent concoction. Others puffed on illicit roll-ups sold under the counter. The community had little in the way of amenities but an off-licence was handily situated around the corner.

Why did they fight? Simply because one gang had intruded onto another's patch. This could be from only a few streets away. And they fought simply because they could.

Ignore the figures about life expectancy or median wages or the number on benefits. This was the flesh on the bones of what it meant to live in poverty. And into this environment the political parties were supposedly pitched in search of votes, in return for their offers of hope. I didn't see a single poster for any party, though one pensioner had hung a Solidarity flag from her third-floor balcony.
What will decide this by-election? Not these poor people, for sure. Nor the competing merits of Labour's Margaret Curran or the SNP's John Mason - or even those of their party leaders, Gordon Brown and Alex Salmond.

My guess is that the biggest influence on tonight's vote will be voters' feelings towards Labour and the SNP, views that will have been formed over decades. Many people will vote Labour because it's in their DNA - or they simply won't vote at all.

There's plenty of disenchantment with the Labour party, but I'm not sure this has strongly coalesced into a willingness to endorse the SNP. It's not as appealing as Mr Salmond would have us believe. Expect a big swing to the Nats - certainly one big enough to keep the First Minister's beaming smile in place, but not one big enough to secure victory. Gordon Brown will live to fight another day.