Post Mortem: Solved most of the clues, managed the rotations correctly, identified Greene but not Braine.
Didn't spot the authors' works in the clues (how Dim am I?).
Didn't complete ring 3 despite a lot of googling, which was sloppy of me.
If I had completed the puzzle and submitted it I wouldn't have written 'British Museum Library' in a circular fashion, so at least I saved myself the cost of a stamp.