Phrasing
Using expressions like "the flying of model aeroplanes" or "aerodrome" seem to indicate someone rather elderly with a somewhat archaic mental reference bank concerning aviation, model or full-scale. Perhaps the local Miss Marple could bring some light to bear ... and, posting letters at Gatwick perhaps provides another clue ???
All set for an instalment of Midsomer Murders (NOT !!!).
I just hope that these threats are the result of someone's dyspepsia before flying off to warmer climes for the winter ..
And my fingers are crossed for the future safety of The Collection and model flyers too.