Hong Kong. (British Post Office In China). 1918. Registered envelope headed 'Netherlands Trading Society Shanghai' addressed to Holland bearing British Post Office in China SG 8, 20c purple and sage tied by oval Registered/Shanghai B.P.O. date stamp with framed 'R/Shanghai B.P.O./No' hand-stamp on face with 'Opened by Censor' label endorsed 'via America' with San Francisco and New York/Reg transits and Dordrecht arrival. Very fine.