Hong Kong. (Air Mail). 1936. Air Mail envelope addressed to Japan bearing Hong Kong SG 124, 10c ultramarine (2) tied by Hong Kong double ring '17th Feb 36' endorsed 'By Courtesy Air Flight' with framed 'By Courtesy Air Flight/ Hong Kong China Japan/ Royal Air Force/ Feb 16th 1936' in violet on face. The flight only reached Shanghai had to complete the journey by ship. Scarce.