20 Baht - Rama VIII Series 4, Survey Dept.

Thailand printed its own currency during the Japanese occupation period, a logistical necessity after the war severed normal access to foreign security printers. The Survey Department — a cartographic and technical agency pressed into emergency banknote production — was an improvised solution, and the quality of the resulting notes reflects those constraints. Paper consistency and ink registration are noticeably variable across the series.

Pick 41 was issued across a two-year window that coincided with Thailand's uncomfortable position as a nominal Japanese ally, its government having signed the military alliance in December 1941 under significant duress.