Also, a couple of people have pointed out that Sangorski used the work of other artists in his books. Yes, I know, illustrations and paintings in the public domain, associated with the poems and writings of the authors.

I don’t consider this a swiping issue, because Sangorski’s private commissions were one-of-a-kind books for private clients, and re-purposing these paintings into the designs was the point. Context means a lot. He wasn’t trying to dodge attribution, he was deliberately incorporating the paintings.