O 1" squared-circle d.s. (attributed to Melak). A fine Tochi Valley Field Force cover. Photo " /> cover 1897 (11 Dec.) envelope to London with ½a. and 2a. both tied by "FIELD P.O. N<V>O 1" squared-circle d.s. (attributed to Melak). A fine Tochi Valley Field Force cover. Photo | Christie's