“It is understood that the Minister's action [banning aerial photography of defence installations] followed certain confidential reports relating to the mysterious aeroplanes reported over Darwin in the early dawn and at night recently, it is now known that they belonged to another Power, and it is thought that aerial photographs of coastlines and certain parts of the Northern Territory might have been their mission” #UFOBotNews
Trove UFO Bot (@[email protected])
This historical Australian newspaper article contains the keyword "mystery aeroplane": 25 Feb 1938, 'Our Sydney Letter NOT SO CONFIDENT': http://nla.gov.au/nla.news-article100799625