THE slums of Dhaka in Bangladesh are an unimaginable place. It’s a few years now since I last visited this claustrophobic world of filth, disease and hunger.

After decades of reporting on some of the poorest communities on the planet, I thought I’d become pretty inured to the sights, sounds and smells of such places, but Dhaka’s slums and others like it around the world always make me think again.

Living in rickety shanties that are frequently semi-submerged in foul water, the people who struggle to survive in this abyss are among the poorest of the poor.

One in 10 of the children who inhabit Dhaka’s slums die before they are five years old. The 50p their exhausted parents might earn for a punishing 12-hour day breaking bricks or hauling a rickshaw in temperatures often in excess of 100F is never enough to buy them food, let alone the medicine that might keep them alive when they inevitably fall ill.

Already vulnerable, such people are open to the worst possible exploitation – slavery. It’s estimated that more than half a million people are enslaved in Bangladesh, and bad as that is it’s far from the worst level in the world.

To witness slavery up close comes as a shock to the system. It forces us to stop and question the core values that underpin all our lives.

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Scotland of course has historical form when it comes to slavery. Only last month the BBC screened a two-part documentary, Slavery: Scotland’s Hidden Shame, that acted as a searing reminder of our nation’s role in such barbaric exploitation.

What the series presented was an in-depth exposé of a passage in Scottish history that for years was conveniently put to one side while we patted ourselves on the back for those contributions that came from a more enlightened Scotland.

It’s been good to see Scotland confront its past shame over participation in this most inhumane of trades. Another sign perhaps of the emerging Scotland I have mentioned before in this column, one re-examining its place in the world and determined to be recognised as having progressive, humane values at its core.

Today, when it comes to combating slavery, Scotland must continue to step up to the plate. This is not simply to make amends for our past but to lead by example as we have on so many crucial issues from climate change to conflict resolution.

Certainly, now is not the time for anyone to become complacent, for slavery did not end with abolition in the 19th century, far from it.

According to the most recently collated figures, an estimated 40.3 million men, women and children are victims of modern slavery. Of these, 24.9 million people were in forced labour and 15.4 million were living in a forced marriage. Women and girls are disproportionally over-represented, making up 71% of victims.

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People often ask just how exactly do you define slavery?

The answer I’ve often felt is well articulated by Walk Free, a global organisation whose mission is to end modern slavery in our generation.

The National:

In short, it defines modern slavery as referring to situations where one person has taken away another person’s freedom, their freedom to control their body, their freedom to choose to refuse certain work or to stop working, so that they can be exploited. That freedom is taken away by threats, violence, coercion, abuse of power and deception. The net result is that a person cannot refuse to leave the situation.

I’ve seen for myself the many forms this malign trade takes.

In Democratic Republic of Congo (DRC) I’ve watched children extract from mines the minerals that find their way into our mobile phones, computers and cars.

In Pakistan I met women and children working from dawn to dusk making mud bricks overseen by gang masters.

In Colombia I saw men work in the sweltering humidity of plantations under threat of violence and in Malawi met small boys who risk their lives fishing on Lake Malawi for businessmen who all but own them. Then there is the forced recruitment of child soldiers and human trafficking.

As the Modern Slavery Helpline highlights too, here closer to home it is often an unseen crime, as it hides in takeaways, hotels, car washes, nail bars and private homes. At least 13,000 people in Britain are estimated to be victims of modern slavery, but monitoring groups say the true figure is likely to be in the tens of thousands.

While modern slavery is most prevalent in Africa, Asia and the Pacific region, we must not for a moment think of it as a product of or blight on such areas alone.

“Modern slavery is a first-world problem,” says Andrew Forrest, co-founder of Walk Free.“We are the consumers, we can fix it,” he insists, and he’s right.

The good news in all of this is that the tightening of the Modern Slavery Act along with a new initiative by the Scottish Government will require many businesses in Scotland to raise their game in monitoring the potential of human exploitation within their supply chains.

Section 54 of the Act, which relates to employers, was introduced across the UK to ensure organisations had procedures in place to curb modern forms of forced labour operating within business supply chains around the world.

Here in Scotland separate legislation too was introduced to refer to the criminal aspects of modern slavery, under the Human Trafficking and Exploitation Scotland Act 2015. Such moves are something to be proud of and a far cry from the horrors of the past in which we actively engaged.

But that is not to say the scourge of slavery does not persist. Last year, more than 200 potential victims of slavery were referred to Police Scotland. Here at home and across the world this most vile form of exploitation still prevails. It is the responsibility of us all to do what we can to make it a thing of the past.