From an article about the Colossus computers used at Bletchley Park, England, during World War II, the machines used to crack the German
Engima high command's cypher:
Despite early worries, valves proved to be extremely reliable. Colossus’ designers realised that most valve failures were caused when machines were turned on and off; therefore the Colossi ran almost uninterrupted from the time of its installation to the end of the war. Such was the prodigious amount of heat pouring from the machine that the Women’s Royal Naval Service operators were reduced to working in their underwear!
Swoon. If there are no pictures to be uncovered, I respectfully request some fan art. (Rule 34 editions optional.) Then let's follow up with a retrospective with the original woman operators today, modeling their literal granny panties.