cover 1847, 1sh Green (5, Gibbons 54), clear to large margins all around, tied by numeral grid cancel on Sept. 1856 stampless folded cover to the U.S., stamp additionally tied by red Philadelphia, Pa. Paid receiving c.d.s., bold red '21 Cents' exchange h.s. credit, very fine, Scott retail $200.00+, Gibbons £450 est.