Hong Kong. ( Official Mail ). 1938. Registered Air Mail envelope from the 'Malaria Bureau, Hong Kong' with oval cachet, addressed to England headed 'On His Majesty's Service' cancelled by Official Paid / Hong Kong ' date stamp in red with 'Registered / G.P.O. Hong Kong' double ring with registered label and 'By Air Mail / Par Avion' label in blue. Nice item.