When an editor at this magazine asked if I had any unwritten books, she’d come to the right person. I would say unwritten books make up the majority of my interior life. They are my regular companions on errands and walks, when a fly hatch of impertinent and largely inconsequential themes, descriptions, scenarios, phrases and connections murmur round my head. How would you describe that man’s distinctive gait? What quality of pressure does frozen grass have underfoot? Why is everyone in Keats’s verse asleep? Did Martin Amis take the plot of Success from A A Milne’s poem ‘Twice Times’, where a good bear and a bad bear gradually swap personalities? What was so interesting about bores to the mid-century intelligentsia? I often come to a halt in the street looking for answers to these questions while shoppers eddy around me, rolling their eyes. Me, I am never bored.

 Sometimes I get a little further than this. To me, a book I might actually write doesn’t come as a single revelation but through accumulation, an unnoticed gathering of items of interest, like when the still air on a winter’s day seems to thicken with interference and then you look at your sleeve and you see it’s snowing.

It was a summer’s day when the thing became visible to me. My children were still young and we went with a friend and her children to swim in a local river. It was late afternoon, flashbulbs of sunlight popping on the water. The children’s small heads shone sleekly, like