Sleepless nights, cloudless skies and the toughest questioner of all

Monday

Edinburgh lies at 55 degrees north. That means that in the summer, it is barely dark at midnight and dawn comes only a few hours later. It also means that I tend to wake up at about four in the morning from May until August. White nights.

So the day, and the week, start extremely early. There is work to do: my New York publishers have asked me to write an ebook novella to accompany the US publication of my next Isabel Dalhousie novel in the autumn. So here I am, at four in the morning, writing about how Isabel receives an electronic invitation to coffee -- an invitation that is immediately withdrawn. This is because the original sending was a computer mistake. Unlikely? Yes, but that is exactly what happened to me last week, when I was completely unintentionally invited to have coffee at an Edinburgh gallery by somebody I had never met. I decided to accept (why not?) and suggested meeting at the house instead. So today I had a stimulating lunch with two members of the philosophy department of the university, one of whom was the owner of the misbehaving computer. We talked about all sorts of things, including the issue of whether one should seek to dissuade people from blaming themselves unrealistically for things for which they are not at fault.

A couple of weeks ago I found myself sitting at a dinner next to Martin McAdam, the chief executive of a company called Aquamarine, which designs a wave-power machine called the Oyster. He invited me to visit them, and I took up this invitation today. The Oyster appears to be efficient, green and infinitely less destructive of natural beauty than the wind turbines disfiguring the country. The hour I was meant to spend with them quickly became two. The way it works is this: waves come in and push a flap that compresses water, which drives a turbine on the shore. Nothing could be simpler, and fish, we are told, approve.

Tuesday

Tom Cunningham, the composer with whom I have collaborated on a number of projects, calls round with David Weir, director of Dovecot Studios, the great Edinburgh studio responsible for the weaving of many important tapestries over the past century. Tom and I are going to write a piece (music by Tom, words by me) about some of the tapestries woven by the studio over the years (including pieces by artists such as Bawden and Hockney). This will be performed in its centenary year, 2012, at the same time as its Edinburgh Festival exhibition.

Wednesday

An American student calls by to discuss my work. She is from North Carolina and has the good manners and charm one expects from those parts. After she leaves, a retired surveyor in his eighties drops by. He has taken to composing songs in his retirement and has written one for Isabel Dalhousie. He sits at the piano and plays it for me. This is followed by a conference call involving Sarah Cleaveland and Kim Doyle, directors of a charity of which I serve as patron, the Alliance for Rabies Control. I recently went to Tanzania to see their work. I met a man whose entire livelihood, his small herd of cattle, was wiped out by an attack by a rabid jackal, and a family who had lost their daughter to rabies following a dog bite. Supplies of anti-rabies serum are not always available; it is not cheap, and so poor people die. It is ever thus.

Thursday

My wife and I take a train to London. That journey down the east coast takes us along Scottish cliffs and then into rolling English country-side. Ripening fields under a cloudless sky; sharp sunlight on the North Sea, often so cold, so steely -- but not today. And then King's Cross Station and bustling crowds. Betjeman's evocative line comes back to me: "Oh merciless, hurrying Londoners . . ." But they aren't merciless, in my view. This is a fundamentally kind and tolerant city -- sorely tested, no doubt, but still welcoming.

Friday

My daughter Lucy graduates from medical school at King's. There is a beautifully conducted ceremony at Southwark Cathedral followed by a reception at Guy's Hospital. For our celebration dinner, we take Lucy and her boyfriend to a restaurant in Notting Hill and walk back along the Portobello Road thronged with people celebrating being alive.

Saturday

The V&A has an exhibition of artists of the Aesthetic Movement. I walk round the rooms, peering at paintings of people being . . . what is the word? Willowy?

It's a perfect, cloudless day. I take out my notebook and start on the tapestry piece - something about weavers who went off to the First World War and left threads symbolically cut. In the evening, we go to Drury Lane to see War Horse, a moving piece of physical theatre.

Sunday

The London Literature Festival. I meet Michael Morpurgo, the author of War Horse, as it happens, for a photographic session and then do my event, an onstage conversation in the Purcell Room with Alex Clark (former Granta editor). Then I face questions, including one from a very articulate boy of about ten or eleven, called Christoph, who floors me with an observation about an inconsistency in the books. The audience applauds him with delight and I give him a prize of £20. Then a signing and an interview with BBC radio journalists making a programme on criminal detection in Botswana (a peaceable republic, if ever there was one, but still with its quota of malefactors). And finally a train to Brighton, to dinner with my sister and niece, before returning to 55 degrees north tomorrow. Being away from home for a short while refreshes: you are still you when you are away, but not completely.

Alexander McCall Smith's "Precious and the Monkeys" (Polygon, £9.99), an all-age tale of Precious Ramotswe as a child, is out now.