I've just read "Looking for the King" by David C. Downing, an American CSL scholar. I have to say, I feel very let down by it. I thought, if you have the chutzpah to include the Inklings as secondary characters in a novel then you really really have to know your men and be sure you have the knack of making them live again in print before taking on anything so ambitious. But it was very disappointing. Downing (or rather his accredited assistants) had certainly done a lot of research, but it was all so flat, dull, two-dimensional, so absolutely bleeding obvious. Box-ticking, button-pushing.
And sub-Dan Brown. An American post-graduate student in England in 1940, researching for his book about sites connected with King Arthur, and his female side-kick. Has previously been in correspondence with CSL so gets invited along first to lunch with CSL in the Turf Inn and then to an Inklings gathering at the Eagle & Child. He finds himself caught up in a quest for the Holy Lance, but all the time they are being dogged by suspicious people, some of whom eventually turn out to be undercover cops searching for Nazi spies, and one who is actually a Nazi spy.
It could have been a great book but was a damp squib. Lip-service only given to the fact that there was a war on.
As for writing about a certain sort of English person in 1940, you have to be absolutely spot-on pitch-perfect to be convincing. He couldn't even be bothered to make sure he was using idiomatic general-purpose English English. A real let-down.