The Oxford Murders - Guillermo Martínez - didn't think much of it to be honest, I am inclined to blame the translator, though of course I have no rational reason for doing so. The fake mathematics done by Seldom is, surely, wrong, for one thing (or am I confusing provability and decidability or something?). And there are more buses from Abingon to Oxford on Sunday afternoons than you would perhaps expect and that the author thinks. Apart from this it reminded me of bad Inspector Morse territory with unconvincing wibbling about maths added.
However, the WTF is from the Wikipedia article on the film: "Professor Andrew Wiles, who solved Fermat's Last Theorem, is represented as "Professor Wilkes" of Cambridge University in the film, and Fermat's Last Theorem is represented as "Bormat's Last Theorem".
EDIT: No, I think I am right and that Seldom's fake maths is wrong, but surely Martínez, having a Ph. D. in mathematical logic, would know that?!