Cover franked with 2 x 1938 2c slate violet GVI issue (SG 309) tied by fine POSTAL AGENCY No.16 cds of IDA SABINA situated on the Upper Berbice river. Addressed to UK with WISMAR and GEORGETOWN transit cds's on reverse. A very rare cancel, this office was previously thought to have only operated from 1943 to 1947, this cover now extending the latest know use by three years.