On 5/8/55 Lewis writes to Dorothy Sayers and says that Baynes' illustrations for the Narnia books are not that good.
Sayers had written that the frontispiece to LWW was arguably blasphemous. Lewis writes her biggest problem was her total ignorance of animal anatomy. "I have always had serious reservations about her (this is sub sigillo)". He did like her ability to draw plants, and also felt she needed the work with an elderly mother to support.
Then on 9/8/55 he agrees with Sayers calling the LWW frontispiece blasphemous, then says Hell wouldn't be large enough to hold all the mediocre religious artists, if mediocre art was literal blasphemy.
I'm thinking the LWW frontispiece (not reproduced in my paperback version) in question is this one:
![Image](http://www.manhattanrarebooks.com/images/Misc/lionfrontis.jpg)
Source:
In my opinion, this frontispiece is not great but not bad either. This opinion of Lewis' is rather startling. My first reaction was to think him hypocritical for writing compliments to Baynes in his letters to her, if he never really liked most of them. But on second thought I think he showed patience with Baynes despite his felt dissatisfaction with her work, rather than hypocrisy.