This was an excellent puzzle with lots of challenges and different devices to keep us on the ball. Thanks eXtent.
I am feeling rather smug as I got the theme without recourse to the internet or any other reference. I was gifted the book when it was first published. And, although I never finished it (as you might imagine it becomes increasingly difficult to read!), it fascinated me and its premise has stayed with me ever since. What a great theme for an Inquisitor.