Lot no. 6134

4 d. vermilion, plate 13, tied by duplex "C51/ST. THOMAS AU 16 73" to entire letter to San Juan, Puerto Rico, here franked for inland postage with Spanish Cuba 1873, 25 c. pearl-grey in horizontal pair, tied by clear strike of oval "ADMON. GENL. DE CORREOS DELA YSLA DE PTO. RICO". On reverse Puerto Rico arrival mark of August 17 (with month inverted). A very attractive and unique combination franking and one of the most important items of British PO at St. Thomas. Certificates BPA (1012) and Graus (1991) (SG Z11+ Cuba53)