1926 (23rd Aug) cover flown by N. Vincent's Air Survey Co., to Port Sweetenham, endorsed and rubber-stamped in black 'BY AIR MAIL', 4c Straits Settlement tied by code "H" 8 AM Singapore double-circle datestamp, 'TANGLIN/SINGAPORE' code "E" sub-office datestamp alongside, 'PORT SWEETENHAM 12.30PM 23 AUG 26' backstamp, minor adhesion on reverse not affecting this rare cover, (BEA.26.13bd - Believed only 5 flown)