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GREAT BRITAIN - OXFORD ERROR OF POSTMARK FEATURING UNDERPRINTS. 1871-72. An attractive collection on two, neatly written up album pages featuring the '613' error of Duplex postmark, mostly on Oxford Union Society underprinted penny reds. We see a couple of single (off paper) underprinted 1d reds & 3 covers with examples of both, the flat topped '3' in '613' & the round topped '3' in '613'. Includes flat topped '3' in '613' range with a single off paper 1d red - plate 134 bearing 'O.U.S.' underprint reading downwards, an 1872 cover to Stow-on-the-Wold bearing Plate 155 1d red tied by (flat topped 3) Duplex & a 1d postal stationery card with same (flat topped 3) Duplex, then, round topped '3' in '613' (off paper) 1d red  plate 124 bearing round topped '3' in '613' cancel & 'O.U.S' underprint reading upwards & a cover to Hastings - plate 119 1d red tied by round topped '3' in '613' Duplex bearing 'O.U.S' underprint reading upwards. An attractive assembly. (3 covers & 2 stamps)