cover 1874 (23 July) envelope from Lurgan, Ireland to Shanghai bearing Great Britain 3d. and 1/- cancelled by "316" duplex and showing on reverse "HONG KONG/HONG KONG TO/SHANGHAE/MARINE-SORTER" c.d.s. (29.8) and very rare oval "CUSTOM HOUSE/SHANGHAI" d.s. in red of which only a few other examples have been recorded. Photo