During a recent trade visit to Jamaica, the Prime Minister let it be known that, what with one thing and another, Britain will not be paying many billions to the countries of the Caribbean in reparation for the crime of slavery. That is not, these days, how we do business.

David Cameron was frank enough. There would be no cheque from Her Majesty’s Government, he intimated, and neither would there be an apology for Britain’s role in the filthy trade. Neither his party nor domestic opinion holds with such gestures, or so the Prime Minister believes.

Instead, in a moment that said much about the man, Mr Cameron employed a phrase. The Prime Minister urged nations born in the slavery ships to “move on”. A politician who has spent years ensuring that Britain remains fixated with two world wars endorsed amnesia.

Mr Cameron then presented Jamaicans with £25 million in “aid”. This will build, if no questions of taste arise, a new prison. Specifically, it will be a clink to house islanders Britain wishes to deport. That is, it will be a facility in which descendants of slaves might more conveniently be held captive. We are devoted, after all, to the rule of law.

Members of the Caricom Reparations Commission were unimpressed. As was pointed out by the Barbadian historian Sir Hilary Beckles, our Prime Minister is related, albeit not closely, to General Sir James Duff, an individual who after abolition in 1833 was compensated for the loss of 202 Jamaican slaves. In some degree, the wealth into which the Prime Minister was born derived from the commerce in human beings.

According to researchers for the Legacies of British Slave-ownership project at University College London (UCL), Mr Cameron’s cousin six times removed, the bastard son of the second Earl Fife, was paid off to the tune of £4,101 and one shiny penny. This was his cut of the £20 million set aside by Parliament in 1837 as compensation – call it reparation – to slaveholders.

It was a lot of money. By a crude inflation measure, Sir James – born in Banffshire, educated at Keith Academy and Aberdeen’s King’s College – got the equivalent of £340,000 for the loss of his human property. Equally, the “labour value” of his four grand might be closer to £3.1 million; its “income value” to £5.5 million. The slaveholders cared nothing for black lives, but they knew the value of chattels and a shiny penny.

The £20 million was borrowed from a Rothschild syndicate and simply added to the national debt. The largesse was defended as an act of charity, given the number of respectable widows and the like whose income depended on distant plantations. The fact remains that slaveholders were paid off while former slaves got nothing. Mr Cameron won’t discuss reparations; Sir James got (as he would not have said) a bundle.

The paramount truth to emerge from the essays in Recovering Scotland’s Slavery Past is that this little country was a big player in a hellish business. Few slave ships sailed from Scottish ports, but Scots were conspicuous in every aspect of the trade. Modern Scotland might well have been founded, in part, on profits from kidnap, torture and bondage.

“The Scotch” were notable as ships’ masters and, especially, as ships’ doctors. They ran plantations in the West Indies and syndicates at home. In the English slave trade ports, Liverpool above all, Scots were ubiquitous. The Glasgow tobacco lords, with their networks in the Chesapeake back country, probably sustained slavery in America as much as any group. In 1815, meanwhile, 65 per cent of all goods exported from Scotland went to the West Indies.

Profits flowed back. “Capital formation”, the bedrock of the road to industrialisation, followed. Crudely put, the slave trade was one of those “benefits of Union” that in the usual tale lifted a penurious country to global economic significance. It turned Glasgow from a small cathedral town to a maritime trading giant. The Scottish habit of pursuing marginal advantages in places ignored by competitors paid off all over the world, but was useful indeed in the slave business.

As Professor Devine describes matters, Scotland’s own amnesia towards slavery has been remarkable. No sooner had abolition been achieved, in fact, than the country had “moved on”. Scottish efforts to end the trade were celebrated; David Livingstone became a national secular saint; and pious Christians stayed mute over the foul origins of much of their wealth. We forgot because we chose to forget.

As Professor Devine remarks, something of a revolution in native historiography has been required. Slavery was missing from the history books for long enough simply because there were no history books and no teaching of modern Scottish history worth a damn. Recovering Scotland’s Slavery Past is an illuminating marvel, therefore. But the very fact that it illuminates is a measure of the darkness that prevailed until recently.

In England, black Britons forced the issue long before Scots had begun to wonder about their history “Yonder awa” – Scott implanted the euphemism in Rob Roy – or about what “Scottish enterprise” truly meant, or even about certain famous Glasgow street names. Like England, nevertheless, Scotland was far more comfortable, for generations, in preening itself over its anti-slavery heroes than in dealing with the complicated truth. As anniversaries of abolition came and went, the truth was simply forgotten, ignored, or erased.

The dozen essays in this book should – but we shall see – make future omissions impossible. Taken together, they form a portrait of a country that once had a pressing need to make its way in the world and no compunction whatever about how that was to be achieved. The hideous truth is that it worked. What Professor Devine calls “Scotland’s Great Leap Forward before 1830”, the national ascent from penury, was in part – other factors were at work, as he stresses – thanks to slavery.

Nick Draper, author of the ground-breaking The Price of Emancipation (2009) and a co-director of the UCL project, also notes from his study of the record that compensation dole “coincided with the beginning of the railway boom” in Scotland, as elsewhere. Scottish banks, RBS and its predecessors in particular, did much business with slaveholders. The backwash of money flowed through the country.

After 1833, compensation was paid to 42,000 slaveholders overseas and 3,500 “absentees” at home. The £20 million granted was just over 40 per cent of the “deemed value” of 800,000 people (much of the rest having been extracted in profits). Of the absentees compensated, addresses have been established for 2,400. Of these, 350 were in Scotland. The figure is greater than a population share, even before mention is made of the Scottish diaspora.

Can we impose present attitudes on the past? If the alternative is acceptance, complicity follows. Scots in the slave trade might not have thought twice about their treatment of “livestock”. They might never have questioned racism, or doubted their right to exploit another human. They might have put their faith in God, work and enterprise. Every page of a book calculated to shatter assumptions and presumptions says this: they knew better. And we should know.

Recovering Scotland’s Slavery Past – the Caribbean Connection, ed. T.M. Devine, is published by Edinburgh University Press, £19.99