I get to my desk (in a very small room at the top of the house) at about 10, and fiddle about with the height of the desk and the chair until I’m comfortable. I have a desk that I can raise or lower according to the state of my aching back. Sometimes I stand at it, and sometimes I have it high up to write at, and sometimes a bit lower to type.

The desk is covered by an ancient kilim, because it looks nice, but that’s not a good surface to write on, so I have one of those green safety cutting mats to support the paper I use, which is A4 narrow lined, with two holes. I love the shape of the A paper sizes. It’s the only one of Andrea Palladio’s recommended architectural shapes (the ratios of room length to width, and so on) that contains an irrational number, in this case the ratio of one to the square root of two. Very handy for illustrating Pythagoras’s famous theorem, in fact.

Nearby is a basket full of coloured pencils, including some of the best of all, the Berol Karisma range, now unfortunately discontinued. For each book I write, the paper is authorised for writing on by means of a coloured stripe along the top edge. I fan the sheets out and colour a stack at a time. The current book is a warm blend of Karisma Pumpkin Orange and Faber Castell Venetian Red. I sometimes think I should make it clear which key I’m writing a particular passage in – D minor, at the moment – but that would be silly, unlike colouring the pages, which makes perfect sense.

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