Hong Kong. (Shanghai Defence Force). 1927. Envelope addrssed to New York bearing Great Britain SG 419, 1d scarlet and SG 420, 1 1/2d brown tied by 'Field Post Office/1' double ring '25th Mar 27' routed via Hong Kong. Field Post Office One Opened at Tifeng Road, Shanghai on March 25th 1927. Ddue to a strike at the 'Foreign' rate of 2 1/2d, only a few correct rate covers exist. The privilege was withdrawn at midday on 26th March when the Chinese Post Office reopened.