I picked up a volume from the library of critical writing (both positive and negative) on C. S. Lewis. It's the first in Scolar Press' Critical Thought Series, which includes such postmodern icons as Foucault. The series editor, George Watson, a former colleague of Lewis, makes a provocative case in the introductory essay that Lewis was much more modern - or postmodern, rather - in his critical thinking than most people recognize or appreciate (and he notes that Lewis certainly would not appreciate such a categorization). Watson suggests that Lewis was perhaps twenty years ahead of his time in certain aspects in his critical theory, such as de-emphasizing authorial intent and taking a formalist approach to fantasy. Though Watson admits that Lewis could never be lumped together with the likes of Derrida, he stresses that Lewis was still well ahead of his time with certain ideas and made very important and often unacknowledged contributions to intellectual history and critical theory. He surmises that the reason a school of thought did not develop around Lewis is primarily due to his contrarian nature and his efforts to play the devil's advocate to modern thinkers. In the collection, Lewis comes in for high praise from such esteemed historians as A.J.P. Taylor and E.M.W. Tillyard. Quite incredible given the current mainstream scholarly opinion of Lewis. I think his contributions to intellectual history are due for a reconsideration.
[Note: I originally emailed this to a professor and thought afterwards that it might make a nice post.]