There was a typography-related question from another list. The fellow says:

I live in west London and one of my local stations is Sudbury Town
(Piccadilly Line), built in 1931, when the Johnson face was very well
established across the network. Despite this, Sudbury Town has its own
typeface, and it ISN'T Johnson. In fact it's not even a sanserif face - IT
HAS SERIFS! All the station signage uses this renegade typeface, including
platform "bullseye" signs, destination, "Way Out" and toilet signage. Why
did this happen? Was it a typographic experiment that went wrong? I'm sure
someone must know. My only reference book which mentions it says "The
signage is unusual and does not conform to the general pattern. Perhaps it
was a typographical experiment."

Any information or links would be appreciated!