Found an auction lot from 2013 that included a WWII 'Field Security' armband.
https://sheffieldauctiongallery.com/...213/page4.html
Lot 96 - A WWII Medal Quintet to 2074982 Sgt. A. Riley Intelligence Corps
History
"On the outbreak of the Second World War (1939-45), 31 Field Security Sections were raised to accompany the British Expeditionary Force in an intelligence role. However, the Intelligence Corps was only revived as a full unit in July 1940, by turning the Field Security Wing of the Military Police into an independent formation."
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