re: Twoflower
Josh Kirby (whose name I used to confuse constantly with Paul Kidby) was the premiere Discworld cover artist in the UK for a long time. Unfortunately, he died a few years back.
His covers were entertaining, but you got the impression that his exposure to the books involved listening through a door while somebody was reading one out loud. There was a lot of leeway in his interpretrations.
I remember the "four eyes" gag. I still have that edition somewhere.