ONE evening James Robertson opened the back door of his house in the Angus village of Newtyle, and found a toad on the step. It started to cross the threshold, then thought better of it, but on several subsequent occasions, Robertson found him – or her – sitting there, as if waiting to be invited in. The creature did not, in the end, enter the house, but some time later he found his way into Robertson’s latest novel, To Be Continued, where he offers trenchant opinions and even, at one point, narrates the tale. Called Mungo, not only can he talk but he has an encyclopaedic knowledge of human affairs and history. Not your common or garden variety, then.

Robertson smiles when he thinks about his unlikely new character. The toad, he says, one sunny morning over coffee in Dundee Contemporary Arts, is an object of fascination and myth in many cultures. Some consider the creature a portent of evil. “Obviously I didn’t want my toad to be that,” says Robertson, looking relaxed and tanned. “He’s quite a difficult customer in some respects and he doesn’t take any shit, but he’s also intelligent and – without getting into this too heavily – we humans think we know lots, but nature knows an awful lot more than we do. Long after I’m not in that house anymore, toads will still be wandering about in the garden. They have been around a lot longer than human beings, even if not quite in the same form. Unless we do something horrendous to the earth, they’re going to be around long after we’re gone.”

It would take a remarkable toad to survive the events of To Be Continued, a rambunctious romp in which Robertson’s cast ricochet through the central belt and West Highlands like squash balls in a rally. This is not, as readers will have gathered, a typical Robertson novel. His previous subjects have included religious bigotry, plantation slavery and a portrait of Scotland’s political landscape in the 20th century. There are elements of humour in each, but there was little opportunity for laughs in his last novel, The Professor Of Truth, about the Lockerbie disaster. By contrast, To Be Continued, with its harem-scarem scenarios and surreal twists, was written to entertain.

“I don’t want people to think it’s a new novel by James Robertson therefore we must treat it with great seriousness,” he says. “Without being too trite, I would like people to read the book and go, ‘Actually I really enjoyed being in that world’, and to come out of it at the other end, and have had a good experience. Not a trivial experience but one that was light, not one where you have to engage all your deep philosophical thinking.”

In the space of 15 or so years, Robertson, who was brought up in Bridge of Allan and educated at Glenalmond College and the University of Edinburgh, has become a leading figure in the literary world, his serious, thoughtful, sometimes provocative fiction capturing the mood of the times. As well as writing, he runs the bijou publishing house Kettillonia, and when we meet hands over his latest publication. It is a sumptuous edition of George Mackay Brown’s early series of poems, Orcadians: Seven Impromptus, exquisitely illustrated by Simon Manfield.

Was his new novel conceived as an antidote to the horrors of Lockerbie, or as an attempt to escape his pigeonhole as a heavyweight author? Robertson, 58, admits he did want “a bit of light relief”. Between that harrowing book and this, he published 365, a collection of 365-word stories written every day of the year, which allowed his imagination and wit free rein. Some of the tales are probing and philosophical, others pure jeu d’esprit and mischief. Reading them, you sense how refreshing Robertson found the process. It also made him want to go further and tackle what every novelist knows is the fictional equivalent of climbing Annapurna.

“I’ve always thought that writing comedy is the most difficult thing to do ... I thought, let’s give it a go and see what happens. I wouldn’t have dared to do that if I hadn’t had the experience of writing those short stories, testing out that humour.”

As his singer-songwriter friend, the late Michael Marra used to tell him, “If it was easy it wouldn’t be worth doing”. One also has the feeling Robertson loves a challenge. The result is a spirited, playful but occasionally poignant novel that made this reader laugh out loud, and finish it feeling uplifted. Fellow journalists, however, might find in it as much tragedy as comedy, in that it revolves around a recently redundant sub editor, Douglas Findhorn Elder, whose life is at a tipping point. When the novel opens, he is stuck on an Edinburgh bus on his 50th birthday, on the way to the funeral of a colleague from his old paper, The Spear. His mother is dead, his father is in a care home, and his relationship with his girlfriend of many years is in even swifter decline.

Adrift, Douglas gratefully seizes the opportunity offered by his erstwhile editor to interview a once famous politician, Rosalind Munlochy, who lives in Glentaragar, a dilapidated stately home in the Highlands, on the cusp of reaching 100. Since these events take place shortly after the independence referendum, his editor wants to know, how did she vote?

To the onlooker, however, it seems clear that for once politics was not the spark that lit Robertson’s imagination. Was it, by any chance, the state of the newspaper industry?

“In a weird way you’re right, it was the impetus. I wanted to write about somebody who was having a crisis in all kinds of ways, emotionally, in his life, because of his breakup with his partner, his father being ill and so on. But also I thought, let’s put him into a job where it absolutely is all coming to an end. What better place in that sense to put him in than a newspaper?

“Douglas goes from that to another place apparently in ruin, and falling apart, this big old house stuck up in a glen in the West Highlands. But actually, which one is likely to survive, which one is likely to be continued beyond the end of the novel? It’s probably the ruinous Highland mansion.”

Painful though the subject might be for those of us still hewing away at the coal-face, there is much mordant humour to be wrung from the antics of Douglas and his diehard friends, who think nothing of returning to the office after a couple of hours in the pub. And it is there that a mysterious malt called Glen Gloming makes its first appearance. In this, as in so many other ways, To Be Continued is an homage to Compton Mackenzie’s Whisky Galore.

For a start, the novel’s appealingly retro cover recalls those of the original Mackenzies. The jacket, and the novel itself, says Robertson, “refers to Compton Mackenzie, to some of those films like Whisky Galore but also I Know Where I’m Going, and even references Brigadoon: that idea of people going on a journey into the Highlands and coming back again transformed, or changed, or having learned or not learned something about themselves.”

At several points in our conversation, Robertson cautions against over-interrogating the novel, yet despite himself there are themes beneath the lighthearted surface that throw up interesting questions, should you wish to probe. One such is mortality, and dealing with old age and death. Although this was not intentional, he says, it in part reflects a difficult year in which Robertson and his wife Marianne have had to cope with close family bereavements. Another, less personal theme is the allure and myth surrounding the Highland way of life.

“What is Highland culture?” Robertson asks. “A lot of people in the cities or in the south of Scotland have very cliched views about the Highlands. On one level there are a lot of cliches in this book and I’m having fun with it, but in some respects I’m reshaping them into something else, I’m playing with those ideas. There isn’t a revolutionary statement at the end of this book that says, we must repopulate the Highlands, or there must be land reform, although I believe these things would be useful and helpful. But I’m also saying there’s a level at which myth and legend and a longer view of change in places like Glentaragar is quite a useful thing to hold onto.”

In the 1930s, 1940s and 1950s, he adds, writers like Neil Gunn and Naomi Mitchison were addressing Highland problems. “These writers are saying, what the Highlands needs is sustainability, and other small-scale development that allows people to exist. You don’t solve the problems of the Highlands by applying non-Highland solutions to it. A lot of what Neil Gunn and Naomi Mitchison were writing about still holds true.”

There is, he says, a “strong element” of Mitchison in the fictional Rosalind Munlochy, “but there are other characters in there”. After a pause, he reflects, “I quite often have wise old women in my books. But Rosalind is not always wise. The deep, dark secret that she thinks Douglas has come to interview her about turns out to be really quite reprehensible.”

That indeed, is another of its talking points. Thus, like the illicit whisky at the heart of this book, To Be Continued has hidden depths that one can roll around the tongue. Alternatively, it can be thrown back neat, with a smacking of the lips, not just for its enjoyable taste but for the cheerful afterglow it creates.

To Be Continued ... is published by Hamish Hamilton, £16.99. James Robertson will be discussing it at the Edinburgh International Book Festival on August 25 www.edbookfest.co.uk