Who is the man in the british museum as mentioned in C.S. Lewis' The Screwtape Letters?

Like all the characters in this book, the man noted as studying in the British Museum (as recorded in Chapter 1) is a metaphorical example of how people give up thinking about reality outside what we encounter on a continual basis. The studying need not have taken place in the Museum, it could have occurred anywhere someone might be serious about asking the question, "Is Christiantity a true and accurate description of reality?" The error that Screwtape boasts about leading this person into, is the idea that something we do not continually come in contact with can not be something important. Screwtape encourages his pupil to do the same with his assignment.