1941, Bang Pa-In Palace issue, 2s., 15s. and 10 baht, 51 mostly bi-coloured imperforated essays in an unissued design (format), exceedingly rare, not recorded in Anatchai Rattakul study of Thai Mail 18361943 (only plate proofs in the issued design being illustrated) and not found in any of the important Thailand stamp collections of the last few decades. Very few simular proofs but in different formats and denominations were offered in the Dr. Pichai Burunasombati collection (David Feldman September 7, lots 10767-10772), the Swanson collection had De La Rue produced Master Die proofs in colour (Torres October 1992, lots 248-250). May 18th 1940 Royal Printers «De Unie» in Batavia (Netherlands East Indies) brought an offer to the Board of the Postal-, Telegraph- and Telephone service in Bandung on stamps and postal stationery. Included were 3 pages with printing proofs of Siam and 1 page with printing proofs of the Netherlands East Indies. Recently a copy of the offer was found with also 4 pages of printing proofs attached, the 3 pages with 51 items of Siam are this lot, the Netherlands East Indies is lot 1559