Glasgow, United Kingdom - It is just before 11am and despite the pouring rain, people are gathering in George Square for the May Day parade.

This is the political heart of the city. Over the years, it has been the scene of protests and celebrations.

In 1919, the British government, fearful of revolution, put machine gun nests in the post office and deployed tanks to quell unrest from striking workers.

Today, the red flag is flying over the City Chambers in honour of the occasion, but the crowd is much smaller, numbered in hundreds rather than thousands.

Scotland the Brave

Willie Gardner is a cornet player with the Unison Kinneil brass band that is playing at the march. Most of the musicians are wearing purple plastic capes to protect themselves from the rain.

"I think it is important that the workers display a bit of unity on a beautiful day like this," Gardner said with a smile.

The band was founded in 1858 by miners at the Kinneil pit in West Lothian. The colliery closed more than 20 years ago and most members now are the children and grandchildren of miners. Gardner said playing at events such as this makes the band feel proud and appreciated.

Glasgow doesn't let them down. As they walk through the city centre onlookers shout encouragement.

Party of the proletariate

The Labour Party was founded in the mines and factories of industrial Scotland, but a majority of working class Scots voted "Yes" in last year's independence referendum. Gardner was one of them and now he is leaning towards the SNP.

"I think the policies the SNP are putting forward have got a lot more appeal. They are a bit more progressive. They are looking to support the local man," Gardner said.

Duncan Fleming, 18, said he feels the same way. The Strathclyde University student is with a group of activists from the Radical Independence Campaign.

They all have red T-shirts with the slogan "Workers make Glasgow". It is a variation of the city's official corporate branding "People make Glasgow".

"There has been a change in Scottish politics and the working class are making their voice heard instead of mindlessly voting Labour," Fleming said.

He lives in the constituency of Scottish Labour leader Jim Murphy.

"He's one of the worst offenders, he claims to be a socialist and working class, but if you look at his voting history and what he actually stands for, he doesn't represent the Labour movement at all.

"So, I'm voting SNP to get him out."

The SNP trade union group said its membership has grown from 1,000 members to 15,000 since last September.

The massive increase is an indication of how many on the left have come to see the Nationalists as the party that represents change.

In their eyes, Labour has become the establishment that it was created to challenge.

Of course, not everyone shares this view. Thomas Laird, 60, was riding along on a mobility scooter plastered with Labour posters.

The failure of trust is not something that can be recovered overnight. You can't push an avalanche back up a hill without very significant effort. David Moxham, Scottish Trade Union Congress

He said he was inspired as a child by Geoff Shaw, a Church of Scotland minister in one of Glasgow's most notorious slums, who was so angered by the poverty and injustice he saw that he went into politics as a Labour councillor.

Laird said simply, "there is no going back."

Frank Toner is a young Labour councillor in West Lothian.

"The UK Labour Party and the Scottish Labour Party have a workplace manifesto," Toner said. "It talks about breaking down exploitative contracts and zero hours contracts, it talks about raising the minimum wage."

These are policies that should resonate with the marchers shouting "zero hours, no way, make the greedy bosses pay". But Labour is finding it hard to get a hearing in this campaign.

Failure of trust

David Moxham is assistant general secretary of the Scottish Trade Union Congress, one of the main organisers of the May Day celebrations. He said people have lost faith in the party.

"I think it has happened because for a long time Labour took its electorate in Scotland for granted. I still think that the Iraq War caused enormous damage amongst the activist base."

"The failure of trust is not something that can be recovered overnight," Moxham added. "You can't push an avalanche back up a hill without very significant effort."

If the polls are right, Scottish Labour is on the eve of destruction. If even ex-miners are deserting them then there is little hope of a last minute turnaround.

What is fascinating is that the challenge has come from the left, not the right.

Last year's independence referendum engaged working class Scots and taught them their votes could make a difference.