It would rather depend on whether it was in his RFC/WW1, his interwar or postwar 'Air Detective'/'Special Air Police' and/or freelance investigator, or his WW2 RAF career phases ..
Of course, the same question might be asked about Worrals
[some of my collection of both are illustrated, but do not clarify ..
(mere guide at) Jet Age Museum, Gloucestershire Airporthttp://www.jetagemuseum.org/
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