I have a keen interest in the way fonts and lettering are generated and these pages from a British Standards book in 1940 detail the exact methodology used to generate the 1940s font used on ARP / Civil Defence / Fire signage.
Also included is the exact size of the various signs. I was somewhat confused why 7/8" was used instead of 1" on the Shelter 'S' signage but someone mentioned saving material (which makes sense) but it doesn't seem to follow through on vertical signs.
I'm including the files as downloads as well.
Courtesy of Roger Miles.
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