The heart of

lightness Alexander McCall Smith counts Donald Rumsfeld and The Red Hot Chili Peppers among his fans, and has a very cool cat. Mary Wakefield talks to him about Africa and 'reality' Alexander McCall Smith wants to show me his cat. `I think he's asleep in the spare bedroom,' says Edna, his cleaning lady, putting down a mug of coffee. 'I'll go and get him.'

`No, no, no!' McCall Smith leaps into the hallway ahead of her. For a big man, he is surprisingly light on his feet. 'He'll come, he will! He'll come if I call him.'

His teenage daughter appears in the study doorway. Edna looks out from the kitchen. I find myself holding on to a small wooden pig carved into the banister rail. Centre stage stands McCall Smith, feet together, arms at his sides. He lifts his chin and pauses, then lets out a mellifluous yodel: `GordyGordyGordyGordy.' Silence. We stare hopefully at the stairs leading down from the spare bedroom. Again: `GordyGordyGordy!'

Suddenly a thin brown cat streaks down the stairs towards McCall Smith's cream-suited trouser leg. He bends down to stroke it. then looks up at me. 'Would you like to see "long-cat"?' My grip on the pig tightens. `Do long-cat, Gordy, do longcat!' In response. Gordon the cat stretches out his legs stiffly in front of him like a little cat rocking-horse, and with a modest smile McCall Smith lifts him triumphantly up above his head, holding the cat aloft like a voodoo priest might a snake.

Eventually, when the surreal feeling wears off, one of deep admiration takes its place. Alexander `Sandy' McCall Smith has written more than 50 books, from The Perfect Hamburger (for children) to The Forensic Aspects of Sleep. Aged 55, he has become a literary superstar with fans worldwide keening for the next in his series about the No. 1 Ladies Detective Agency in Gabarone, Botswana. Last year he overtook John Grisham in the bestseller lists, this year he is Author of the Year for the British Book Awards, the Booksellers Association and, as of last week, Waterstone's. In addition, he is professor of medical law at Edinburgh university; he plays the bassoon in an orchestra which he co-founded, and until very recently was head of the International Bioethics Commission of Unesco and vice-chairman of the Human Genetics Commission. All this, and he still wants to show me 'long-cat'.

Over lunch in his garden — tomato soup and smoked salmon on a white, wrought-iron table — McCall Smith talks about the success of his African detective stories. `It's amazing,' he says in between mouthfuls, `we've sold about two million copies in America and nearly five million world-wide. We're being translated into 30 languages: French, Italian, Danish, Portuguese . . . um, Japanese, Greek. . ' he looks up, `Finnish, Dutch. I've even been discussing the film of the No 1. Ladies Detective Agency with Anthony Minghella. He read the books and loved them.'

Everybody loves McCall Smith. Dick Cheney and Donald Rumsfeld are fans, and even the President's wife, Laura Bush, has sent him a herogram. Flea, the tattooed, cult guitarist with the Red Hot Chili Peppers urges young rockers to read McCall Smith in his Internet diary: 'They are really fun books and make you feel like human beings can have worthwhile lives. I highly recommend them if you like to be happy.'

The main draw seems to be Precious Ramotswe, heroine and proprietor of the No 1. Ladies Detective Agency, a 'traditionally built', middle-aged African woman with a fondness for bush tea, solving local mysteries and Mr J.L.B. Matekoni of Tlokweng Road Speedy Motors. Ramotswe shares, with McCall Smith, a belief in the basic decency of human beings, but is otherwise as practical as he is whimsical. `I never have a problem writing about her; I enjoy her company,' says McCall Smith happily. `Mma Ramotswe believes the best of people. It's an attitude you find a lot in Botswana. They have a way of being which involves respect for others, a culture of appreciation and courtesy. Have you been to Africa? Yes? Then you'll know what I'm talking about. The pace is slower and so people take time to greet you, they engage with you and when they talk to you they look you in the eye.' Here, we are obliged to make eye contact. His are grey, and steelier, given 'long-cat', than I would have imagined.

You never portray any of the bad things about Africa, I say, the Aids, the starvation, murder-rates. Isn't that a bit escapist?

'Well,' he says, `Africa has traditionally been perceived as the dark continent, full of chaos. The West, especially America, has a fixed caricature of Africa as primitive and aggressive and I wanted to redress the balance, show Africa's gentler side. I'm not saying that none of the bad happens, just that we shouldn't dwell on it. All entertainment, especially fiction, recently has obsessed on the pathologies in the human condition, the problems and the kinks. But art doesn't have to be bleak.'

Shouldn't it be realistic, though?

`Nothing is worse than this modern obsession with "reality",' he says, looking concerned. `Nothing is, in fact, less real. It's just all about degradation.'

As McCall Smith eats smoked salmon, I look at the giraffe on the knot of his tie. It's lying on its back with its legs pointing towards his chin. Underneath the Panama, one lock of hair is longer than the rest, which makes me suspect he has cut it himself. He doesn't seem to fit the stereotype of an American celebrity, but every day brings more fan mail from across the Atlantic. Women write to say that Precious Ramotswe has changed their lives, that she brings comfort to the terminally ill and hope to the spiritually disorientated. One psychotherapist has written to say that he successfully treats chronically miserable patients with doses of the No 1. Ladies Detective Agency. So what do rock stars, depressives and warmongers get out of a portly woman detective solving village disputes? How did Precious Ramotswe become a cult hit in a country with a boundless appetite for disaster movies like The Day After Tomorrow?

'I'm not sure I know the answer to that, but certainly the response I've had has been astounding,' says McCall Smith. He pauses and eats some bread. 'One theory I have is that, apart from their government, the Americans are very kind people who want to be liked. They can't bear this global view of themselves as violent, hateful warmongers, and so they respond to the kindness of Mma Ramotswe. I think also people are reassured by the size of the problems she has and her way of sorting them out. She tries to find a way of letting everybody live with each other, to draw the wavy line between opposing desires rather than saying one is right, the other wrong.'

Unlike George Bush, I say enthusiastically.

'Well, maybe,' says McCall Smith, frowning slightly at my eagerness to do a man down.

After lunch, we carry the lunch trays back upstairs, and as McCall Smith makes coffee I try to plumb the depths of his optimism. He doesn't believe in God, he says, although he admires belief — he just thinks that people are basically good and that unpleasantness, aggression and violence should be aberrations, not the norm. 'You can tell that people would like to be decent, because they respond well to politeness,' he says. 'I think perhaps that Western cynicism has had a sort of snowball effect because we've now reached a point where there's a total lack of forgiveness in our society. Look at Africa: for all its faults, there's definitely a culture of forgiveness there.' He offers me a biscuit. 'Perhaps it's her willingness to forgive that attracts America to Mma Ramotswe.'

Two new books by Alexander McCall Smith will be published this year. The first, In the Company of Cheerful Ladies (Polygon, £12.99 hdbk) will be published in August and the second, The Sunday Philosophers' Club (Little, Brown, £14.99 hdbk) will be published in September.