The illustrations alternate between line and colour. I think the latter are more successful. As you can see they have a lithographic quality that is rather attractive. I particularily like the narrow colour palette. They also show the influence of John Piper, which for me is seldom a bad thing. (In a the notes at the end of the book - first mention of the artist at all, por chap - it states that 'the colour drawings were worked out as auto-lithographs.')
As I type this post I am listening to 'The Late Paul Barnes Show', broadcast orginally late Saturday night/early Sunday morning. (Good old i-player) It's one of the best, if somewhat eccentric, jazz programmes on British radio, and local radio too. I recommended it.