My basic impression of Harker's book was that he appeared to marshalling 'evidence' he liked the look of to deliver what he considered would be a knockout blow against somebody or some people, but then never swung his fist forward. I was left rather bemused. I was interested to learn from Maggie Mackay of the School of Scottish Studies that she was similarly frustrated by the lack of delivery at the end. We were left puzzled at who it was he was trying to convict.
From the above it looks like others managed to get the point more clearly than we did.