The highlight of the second day of the Charleston Festival was Robert Harris talking about his novel, An Officer and a Spy, which I haven’t read and now want to.   He was admirably straightforward in describing how his interest in the Dreyfus Affair derived from a commission from the filmmaker Roman Polanski;  had involved a bit of research, including the use of a 1900 Baedeker Guide to Paris, which told him about the relevant restaurants;  and then a mere six months of writing from 5.30 in the morning to lunchtime.   He compared his technique to that of Dickens and Trollope, believing that the best novels should be written without pretention.   He was offset by discussion with Hilary Spurling and came across as impressively convincing.