Thailand. (Post Office Stationery). 1938. Registered Post Office stationery envelope headed with printed bilingual 'On Postal Service' addressed to Bangkok with triangular hand-stamp and bilingual Udaya date stamp (railway ambulant) '28th June 38' on reverse with 'R/ Siam/ Udaya' registration label and arrival in Bangkok '30/6' on reverse.
Official mail from the Government Offices was posted unstamped with the name of the Ministry, the title and signature of the official. The mail was received in the Post Office and registered if required. Pre-War Official mail is scarce.