My trip to the British Library provided me with some useful illustrations associated with the development of the stamp. Firstly there are some of copies of Alan Batley’s sketches of the Post Office building, complete with annotations. There are two from the early days with only a couple of floors, one front view and a 3d view for all of you who are curious as to what the side of the building looks like.

These demonstrate that the book was still being written while the stamps were being designed. A further sketch shows a later version with the extra floors required by the story when Moist was experiencing the unreality of the place. This one seems to be the final chosen illustration.