Former First Minister Lord McConnell will spend five days next month living on £1 a day.

He tweeted an invitation to the rest of us to join him. His aim is to support Below the Line, a charity that raises funds and awareness of the billion-plus people living in extreme poverty.

Why not join him, was my first thought. It would be an excellent exercise for body and soul. The money I save or raise could go to the charity. I'd feel good about myself and I'm sure I read somewhere recently that fasting reboots the body's immune system. I could help them and help me.

The intention is admirable. But what the experience won't do is give me or any other participant any clue of what it's like to be near destitute in the developing world. A year on £1 a day might offer a glimmer.

Five days with an empty fridge; it doesn't even come close to mimicking what it's like to be hard-up here, to bump along the bottom of our affluent society barely making ends meet.

Five days of fasting doesn't involve the constant calculation of how many mouths can be fed on what cash remains. It fails to replicate the stomach-churning anxiety at the sight of a heating bill or the realisation that a child is out-growing their shoes. And it can't offer any insight into how it feels to work all week yet not earn enough to get by without benefits.

What a scandal that is. It's morally wrong. It's unjust and tailor-made to stir up justifiable anger in the population. Don't take my word for it. Steve Hilton, former adviser and strategy guru to David Cameron, says so plainly in his new book More Human.

Mr Hilton says all firms should have to pay their staff "a business friendly living wage". In exchange he suggests offering a cut in business taxes.

As a younger man he believed theoretical economists who argued that higher wages meant fewer jobs. Then he saw what happened when the minimum wage was introduced. There were no catastrophic consequences. He said recently in an interview: "It seemed outrageous that we should tolerate a situation where people work incredibly hard yet can't earn enough to live on.

We have to do something about this. Anyone who works a full week should be able to live on it."

Can anyone disagree? Scotland claims to sit a great deal further to the left than Mr Cameron's former advisor so why haven't we done more to tackle this injustice? Last night a BBC Scotland documentary, Low Pay for Life, highlighted that only 10 of our 50 biggest employers pay all their staff the living wage. Half of Scottish Premiership football clubs employ staff paid below the living wage.

It's a subject that made it into Nicola Sturgeon's party conference speech in March. She said: "The basic principle of a fair day's pay for a fair day's work is ... fundamental to our sense of society. But in Scotland today nearly half of all adults and more than half of all children who live in poverty are in households where at least one parent is working. Within the next 12 months we aim to have 500 companies signed up and paying the living wage to all of their workers."

I hope she will be as good as her word. The Poverty Alliance yesterday named BrewDog as the 200th employer recognised by the Scottish Living Wage Accreditation Initiative.

This is good news for all the employees who are thereby raised to the minimum standard at which our society should reward any worker. But is it an achievement we should shout about; or blush about?

Let me put it into context. Scotland has 335,015 private sector enterprises providing 1.1 million jobs. Of these, 2,295 employ 250 people or more. There are 3,780 middle-sized firms with between 50 and 249 workers. The vast bulk are small businesses with up to 49 employees.

There may be a number who pay all their employees the living wage but are not accredited. I suspect many others don't pay it to everyone; or they may turn a blind eye to work they contract out such as cleaning and security.

While 500 accredited firms by March 2016 sounds impressive, it's going to take a long time to get to 5,000 or 50,000. At this rate it could be decades before working in Scotland guarantees a fair wage.

The First Minister has told Westminster she wants more powers to address the issue. But in January Brent Council in London offered reduced business rate discounts to firms that paid the living wage. Around 200 companies were expected to take advantage of savings that ranged from £250 to £5,000. The Westminster Government will meet half the cost.

It could it be done here, now. The Scottish Government controls business rates. It said yesterday that new legislation may soon give councils the power to offer added rates relief locally. This could be used to support businesses who pay the living wage.

And should it? Absolutely. The money would come out of Scotland's budget, whereas welfare payments are met by Westminster. But some issues have a moral imperative. It's actions not words that show the calibre of a government.

Mr Hilton proposed the business tax incentive as a way of avoiding job cuts should the living wage be made compulsory. This is how it would work. Instead of the tax revenue supplementing wages by paying benefits to people in full time work, the employer's tax burden would be cut.

It's win-win situation.

We rail against the abuse of zero-hours contracts. We are aghast that so many people have to use food banks. But isn't the number of people working for less than the living wage also a wrong that needs righted? The only way that most of us can provide for our families and take our place in the world, head held high, is to do a decent week's work. There is a real fault line in our society when people who do that still have to claim benefit.

It is bad for their morale and it is a blot on us all that this situation is tolerated.

Julia McGahan, Living Wage Programme Manager at The Poverty Alliance, says the cost of bringing employees up to the accepted £7.85 an hour can be offset by benefits to their employer. There is evidence of increased productivity and reduced sickness levels as staff morale rises. There are also reductions in the cost of recruitment and training because employees are more loyal.

It seems that everyone's heart is in the right place on this issue but aren't we far too complacent about the rate of progress being made? Certainly 200 firms behaving decently is a plus and 500 by March 2016 will be an improvement. But at that rate, unless there is a snowball effect, we'll still be grinding away at a just wage in a decade.

Families facing yet another week of scrimping and making do shouldn't be asked to wait so long.