Another fine illustrator not mentioned much these days is H.M Brock, even though he only died about fifty years ago (O Tempo!). He produced a huge range of illustrations (mostly black and white) for novels but my personal favourites are the series of images he did showing how the use of electricity would have changed history. I have the complete set of twelve but they are framed and I am loathe to get them out to scan or photograph. Here is a link to reproductions of four of them:
You can also find information about H.M Brock and his brother, C.E. Brock- also an illustrator- here in wordpress:
and here at another blog site:
which belongs to Phil Beard, another fan of illustration.