Where better to meet Sir Tom Devine than in Glasgow's Merchant City?

As the man who has been described as the "doyen of his field" and "as close to a national bard as the nation has" often has reminded us, it was in this square mile that Glasgow was transformed from a dozy, dear green backwater into the fabled, pulsating, money-grabbing Second City of Empire. Here were the HQs of the tobacco lords and the cotton kings, the sugar czars and the coal and iron mongers. Their legacy is still evident in the monuments and buildings, constructed on a scale commensurate with their power and influence and delusions of grandeur. But it lies also in libraries and archives, waiting to be interpreted and narrated by the likes of Sir Tom and his colleagues.

He enters the howff as if unsure of who he'll find inside. He's wearing shades, a leather jacket and denim jeans. He could be a Mafia hitman casing a joint or a debt collector in pursuit of a defaulter. We sit at a trestle table in the patio not, one suspects, because he's eager to top up his tan, but because of problems with his eyesight. Recently, he's undergone several wince-making operations on his left eye, to little avail. "I've only got 16 per cent vision in it," he says, matter-of-factly, "no real vision at all."

For the moment, his other eye is fine, which means he can read and write, but the future is uncertain. "I think the worrying thing is the good eye," he says. He shares a predicament with his friend Gordon Brown, the former prime minister, who lost sight in his right eye after a rugby accident when he was 16. "I know he was troubled by potential retina problems in the good eye when he was in Downing Street. And that's the worry, because the last session I had with my surgeon we spent the whole of it with him trying to advise me and recognising signs in the good eye."

Perturbing as that undoubtedly is, it is compounded by a dispute with an optician over the original diagnosis. There is, therefore, the possibility of legal action, down which route Sir Tom is hesitant to go, knowing only too well that it will be time-consuming and potentially costly. Though combative and generally inclined to engage in argument, he is aware that at 68 he should not expend vital energy dealing with lawyers which he could direct more profitably elsewhere.

He also has other things on his mind, the first of which is his imminent retirement from Edinburgh University, the second being the bestowal of a knighthood, in the Queen's birthday honours list. Henceforth, he must be known as Sir Tom, though whether this will gain him upgrades from cattle to banker class remains to be seen. His family are understandably chuffed and so, one suspects, is he, though he is careful to temper his enthusiasm. "I know it's a cliche," he says, "but this is in honour of the remarkable transformation of Scottish historical studies over my life." It is also, it would appear, the first time a Scottish historian has been knighted, so long - as he notes - "as you discount Sir Walter Scott". He sniggers in his Muttley-like manner, aware that by associating his name with that of the Wizard of the North he is inviting a blitzkrieg of brickbats.

Irrespective of what one thinks of such favours, the knighthood is yet another addition to Sir Tom's extraordinary CV, which runs to more than 20 pages. There are few pies untouched by his fingers. Apart from his day job as a senior research professor at Edinburgh, he has sat on countless boards and is a member of many societies and associations. Were he so inclined he could put more letters after his name than there are in the alphabet. His bibliography is likewise impressive and extensive, comprising numerous articles and books. His book, The Scottish Nation, first published in 1999, in which he traced the story of Scotland from 1700 almost to the present day, was a huge bestseller, eclipsing sales of Harry Potter, albeit only for a week or so. It was quickly - in historiographical terms - followed by two successful and critically-acclaimed sequels, Scotland's Empire and To The Ends Of The Earth, which First Minister Alex Salmond said was "filled with fascinating descriptions".

More importantly, perhaps, Sir Tom is that rare beast, a public intellectual, able to engage with anyone, be it his peers in "the academy", book festival audiences or, on one notable occasion, inmates at Barlinnie, whom he addressed on the subject of sectarianism. The way he tells it that was akin to Johnny Cash's famous concert at San Quentin, made all the more memorable by the intervention of one prisoner who told him that the reason why there was no sectarian problem inside the prison was because there was no access to alcohol.

From Sir Tom's point of view, that is instructive. History - "the queen of all disciplines" - is less to do with paper than people. It is also, as one of his fellow historians has intimated, as much a matter of personality and background of the writer as of objective investigation into historical fact. In essence, every historian cannot help but bring to the table something of him or herself. Nobody can completely divorce themselves and their histories from their subject.

Throughout Sir Tom's work, one detects the hand of a man trying to decipher myths and articulate uncomfortable truths as empirically as he is able. Towards the end of The Scottish Nation, he reflected on deep divisions in Scottish society and the reality that while those living in more affluent parts of the country can expect to live to 80 and beyond, others living in the poorest areas won't see 60. "This depressing picture," he wrote, "helps to explain the incomprehension of many middle-class Scots when they read that their country is a drugs blackspot and one of the murder capitals of Europe … Their reactions reflect the deep social divisions within urban Scotland where the new affluence of the many has not substantially eased the living standards of the poorer minority." Erasing such divisions, Sir Tom concluded, by finding role models for children without them, and employment for those families where that was an alien concept, was the "main social challenge" facing Scotland's tribunes in the years ahead.

It was both heartfelt and hard-headed. "I tend to be very conscious of the downtrodden, of those who have suffered," he once said. His upbringing in postwar years on a Motherwell scheme was formative. The Devines were not poor but neither were they loaded. His father was a schoolteacher and, in the 1930s, one of the first Irish Catholic MA graduates from a Scottish university. He attended an all-boys Catholic senior secondary, having passed the Eleven Plus examination. The vast majority of his contemporaries were consigned to junior secondaries and thus lost the opportunity of going to university. Sir Tom stopped studying history in year two at his secondary, because it was "so ineffably badly taught". He did geography instead, which was the case with many of his generation. On that front at least, he detects a marked improvement. "It's now much better taught," he says, "and much more imaginatively."

He went to Strathclyde University and remembers his years there through a rose-tinted prism. It was the 1960s and Sir Tom preferred The Shadows to The Beatles, perversely believing Hank Marvin could out-strum George Harrison. Lest anyone disagree, he repeats a mantra credited to Harrison: "No Shadows, no Beatles." Back then, the intake of universities doubled, fees were unheard of, and there were generous grants which made life more than bearable. Most of his fellow final honours year received several job offers, unlike today's students, who would not get a sniff at a university post without a PhD. Sir Tom was hired by Strathclyde less than a year after graduating and a few months into his doctoral research.

"I remember going back home to see my mother and saying, 'I don't have to finish that damned PhD.' The sheer innocence of it! Now there would have to be at least one book, considerable post-doctoral experience, etcetera, etcetera. And that's not too bad. But in a sense the main thing is that the young people who are coming in don't recognise this as a problem, because they don't know anything other." What's been lost, he says, is thinking time. "It's essential for our business to have time to think and reflect. Whereas virtually everybody is on a kind of roller-coaster now, a conveyor belt."

He has been in academe ever since, moving eventually from Strathclyde to Aberdeen and from there to Edinburgh. His subject, however, has remained the same; his fascination with - and love of - Scotland has never palled. Whereas previously interest in Scottish history was limited to Mary, Queen of Scots and Bonnie Prince Charlie, this has gradually changed over time. Ironically, Sir Tom reckons, this was partly because of basic failings in its teaching in schools. Consequently, many Scots felt that they had to discover for themselves the real story of their country's past. History's re-emergence also coincided with the rise of the SNP and the publication of popular books by the likes of Nigel Tranter and John Prebble. Finally, and doubtless more significantly, academic historians, several of them English, began to take Scotland seriously, notably TC Smout, whose History Of The Scottish People, which focused on the majority of the population, was incalculably influential.

History, as Sir Tom is well aware, is like a palimpsest. Each generation of historians examines the work of previous generations and adds their own layer. There is no such thing as comprehensive or definitive history. Timing, too, is key. Sir Tom has said that had his two most popular books - The Scottish Nation and Scotland's Empire - been published 50 years ago there would hardly have been any interest in them. Now people are eager to know about the country in which they live and what happened in the past. "Sometimes," says Sir Tom, "I envy creative writers. I don't envy the fact they've got a completely blank page. But they don't have these years of preparatory research and reading before you can get down to the creative act of composition."

His response to retirement is ambivalent. He'll not be sorry, he says, to say farewell to the bureaucracy and managerialism which plague modern university life. Nor will he be unhappy to see the back of "the routine and the so-called rigorous examination by outside bodies". On the other hand, he will miss the structure which comes with working within a behemoth like Edinburgh University. Ultimately, though, he need only retire when he wants to. He cites the case of a double Nobel prize winner who, when he reached the age of 65, cancelled all his journal subscriptions and took up boat-building.

The chances of the new knight doing something similar are pretty slim. He hints at another possible role but declines to be specific. There's a lecture tour in the Far East and he might return to writing essays of which he did more in his early career. This will please his wife, Catherine, he intimates, because it will get him out from under her feet. "That will ensure her at least a degree of mental stability."

In the meantime, there is the small matter of the referendum. Sir Tom has always been careful not to identify himself with a party or a policy, though he made it clear he was "gung-ho" for devolution, which he felt was long overdue. Whether he feels the same about independence he is not saying. What he will say, however, is that were there a Yes vote, "it could potentially transform things. Because it could then become a crusade to remake the nation". And were it to be a No? He recollects what happened in the aftermath of 1979, when a number of intellectuals left Scotland. "Would you see the same diaspora again? Because the sense of absolutely frustrated expectation would be much deeper. There'll be a collective collapse of nerve, almost a nervous breakdown. Not literally, of course. I mean there will be a tremendous and deep sense of disappointment."

If that seems dangerously close to a prediction rest assured it is not. Sir Tom Devine does not do the future and is wary of the present. Neither, as he insists, is his period. The past is the country in which he will always live most contentedly. n

Sir Tom Devine will be in conversation with Gordon Brown at the McEwan Hall, Edinburgh, on Monday at 5.30pm. Visit www.ed.ac.uk/news/2014/tom-devine-lecture for ticket information.