Don’t go to Alexander McCall Smith if you like your crime novels red in tooth and claw. His mysteries are made up of the everyday and the unglamorous — truant daughters, unfaithful husbands, cheats and charlatans — the little aberrations and moral collisions that crop up in most of our lives. His canvas is small, his portraits intimate, yet McCall Smith, creator of the inimitable Precious Ramotswe, presiding deity and founding mother of Botswana’s one and only No. 1 Ladies’ Detective Agency, manages to hold up a vision of life that is often as true as it is entertaining.

Which is perhaps why his books make it to international bestseller lists. And prolific as he is — the genial 60-year-old Scottish author has of late been writing an astonishing four novels a year — more titles may be headed that way. In fact, he has just finished the 10th book in the No. 1 Ladies’ Detective Agency series, he tells me when I manage to snatch some time with him during his visit to Calcutta earlier this week. Inevitably, the conversation turns to that feisty lady — the generously-proportioned, warm-hearted sleuth Mma Ramotswe, who solves the quotidian problems that come her way with her native intelligence and wit.

“No. I Ladies’ Detective Agency started off as a short story which later developed into a novel,” says McCall Smith, speaking with the clipped accent of the upper class British and without, one might add, the faintest trace of the Scottish drawl. He remembers a large African woman he saw in Botswana once — a woman who was chasing a chicken. “She caught the chicken and wrung its neck and I remember thinking that I would like to write about someone like her some day. Eventually, Mma Ramotswe came to me, but I didn’t know then that she would change my life.”

She certainly did. For until the late 90s, which is when the Mma Ramotswe novels began to fly off the shelves on both sides of the Atlantic, McCall Smith had had a distinguished career as a professor of medical law at the University of Edinburgh. Writing was always a passion but to be indulged in only on weekends. And he wrote rather a lot of children’s books to begin with.

Why did a professor of law choose to write children’s books? “Well, it happened almost by accident,” he replies. A Scottish publisher ran a competition for manuscripts and he sent one along in the children’s books category. It so happened that he won, and that encouraged him to write more children’s books.

But all that changed with the phenomenal success of Mma Ramotswe’s exploits. McCall Smith gave up his day job as an academic and turned to writing full time. Though something of a Johnny-come-lately, it wasn’t long before he had built up a formidable oeuvre. He was writing in quick time now and besides the regular additions to the Mma Ramotswe canon, he wrote other successful series such as the 44 Scotland Street novels and the Sunday Philosophy Club novels — both of which are set in Edinburgh. The latter, incidentally, feature yet another amateur female detective — the cultured and perspicacious Isabel Dalhousie.

Despite his obvious preference for the genre, McCall Smith does not feel that he has been particularly influenced by other writers of detective fiction such as an Arthur Conan Doyle or an Agatha Christie, who created Miss Marple — that classic prototype of the unobtrusive female sleuth. “I’ve read my fair share of those, of course, and enjoyed them too,” he says. “But to me detective stories are more a vehicle for talking about society and psychology. For example, a detective agency in Botswana makes a perfect setting for bringing in a whole variety of people.” Hence the genre becomes almost like a novel of manners in his hands, leavened as always with his wry, understated humour.

So not for him the blood and gore of murders most foul, or the grisly trail of bodies everywhere? “Oh no, no,” he laughs. “That’s more in the line of my friend and neighbour Ian Rankin,” he says, referring to the Scottish crime writer famous for his noirish Inspector Rebus novels. “In fact, you know, he came to live two doors down from us. And a week later, there was a murder in the neighbourhood!” he chuckles. “And I told him ‘Well, there you are!’”

Though Edinburgh and its sights and sounds have dominated his adult life, McCall Smith is, in a sense, a child of Africa. Born in Zimbabwe (then Rhodesia) — his father was a public prosecutor in Bulawayo — he spent his entire childhood there, before moving to Scotland to study law. “It was an interesting life in many ways,” he recalls, “But it was not a very happy place. It was a transitional period, the tail end of the British empire…” His voice drops almost to a whisper when he talks about the grotesque misrule in Zimbabwe today. “What’s happening in Zimbabwe is very sad…” he says and you can sense his obvious distress.

But he brightens up when we talk of Zimbabwe’s neighbour Botswana — the locale of No. 1 Ladies’ Detective Agency. “Botswana has been a tremendous success. There is very little corruption there and the people are remarkably nice.” It’s a country he knows well, having worked with the University of Botswana to help set up a law school there. “When I first arrived in Botswana in the early 80s, I felt that it was a good place,” he says.

That feeling of goodness resonates through the Mma Ramotswe books as well. The world of Gaborone, Botswana, has its share of vice and villainy, and its occasional outcrop of evil too, but on the whole, it is a kind and humane place where people lead reasonably tranquil lives. And that’s a far cry from the images of cruelty, corruption and crushing poverty that emanate daily from Africa’s smouldering heart of darkness.

“Some say that I present an idealistic vision of Africa. I think that’s a bit unfair, actually,” he says. For Africa is not an unrelieved monochrome of horror. “There are huge problems,” he admits, “and people must write about them. But there are also large numbers of people in Africa who are leading lives of dignity and worth with a great generosity of spirit. It is important to write about them too. Unfortunately, the good news is not headline stuff,” he laughs ruefully. “And the decent lives of decent people are usually not very interesting from the point of view of literature.”

His readers certainly won’t agree with that. Especially not the ones who are hooked to his 44 Scotland Street novels, which were all serialised daily in the newspaper The Scotsman. A serial novel — Charles Dickens was its great exponent — is not particularly easy to pull off, but the furious urgency of keeping the story going has now become almost second nature to him. “I like to have at least 30 chapters written before I start,” he reveals. “But sometimes I am only three episodes ahead and that’s living dangerously!”

It helps that he can bang out a pacy, 1100-word chapter without too much ado. In fact, he can write as much as 1000 words an hour. “I’m usually able to write about 4000 words a day. I’m aware of my good fortune in that respect,” he says modestly.

In between speed writing memorable characters and situations, McCall Smith finds time to dabble in a bit of music, play the bassoon or the sousaphone. He and his wife, who is a doctor — his two daughters are also medical students — set up the whimsically titled Really Terrible Orchestra that has now become something of an institution in Edinburgh and even has a few imitators. “We are very, very bad,” he laughs. “We make a terrible noise. But people love it, because we are also very funny. It’s funny seeing people trying to play well and getting lost. We often don’t finish at the same time!”

The Really Terrible Orchestra is to hold a concert in New York on April Fool’s Day (sic) but right now, McCall Smith is really terribly excited about something else. The No. 1 Ladies’ Detective Agency television series, a BBC and HBO co-production, should be ready in March. His next Mma Ramotswe outing, Tea Time for the Traditionally Built, is also going to be published soon. “There’s a lot of tea drinking in my books,” he tells me, smiling. “That’s because I am a great fan of tea. And I am happy to report that it’s Assam, and we never use tea bags!”

Well, it’s not just tea — there’s a lot of sympathy in his books too. And a sense of old world charm and respect for the decent things of life. It’s a heart-warming brew and McCall Smith knows how to serve it with a smile.