cover 17c black (11; S.G.19), two singles tied by barred ovals to Aug. 1866 cover endorsed, "Steamer via Portland and New York", from Chatham to London with red arrival datestamp on the front and Chatham, St. Stephen and St. John datestamps on the reverse, part of address excised, otherwise very fine and considered to be a unique franking to pay the double rate, with 1959 R.P.S certificate, ex Jarrett, Argenti, Kanai

Details
cover 17c black (11; S.G.19), two singles tied by barred ovals to Aug. 1866 cover endorsed, "Steamer via Portland and New York", from Chatham to London with red arrival datestamp on the front and Chatham, St. Stephen and St. John datestamps on the reverse, part of address excised, otherwise very fine and considered to be a unique franking to pay the double rate, with 1959 R.P.S certificate, ex Jarrett, Argenti, Kanai