unused Block of Four  -- ditto 1892 framed 3f. 50 (in black) inverted on 5f. grey block of four from the top of sheet with interpane margin at left, fresh and quite well centred, one stamp lightly mounted otherwise unmounted mint. Very fine and scarce. Foundation Certificate (1959), COB CP5 (CU 1); B.F. 28,500+. Photo
unused Block of Four -- ditto 1892 framed 3f. 50 (in black) inverted on 5f. grey block of four from the top of sheet with interpane margin at left, fresh and quite well centred, one stamp lightly mounted otherwise unmounted mint. Very fine and scarce. Foundation Certificate (1959), COB CP5 (CU 1); B.F. 28,500+. Photo

細節
unused Block of Four -- ditto 1892 framed 3f. 50 (in black) inverted on 5f. grey block of four from the top of sheet with interpane margin at left, fresh and quite well centred, one stamp lightly mounted otherwise unmounted mint. Very fine and scarce. Foundation Certificate (1959), COB CP5 (CU 1); B.F. 28,500+. Photo