THE "GLASGOW/159" BARREL TYPE DUPLEX ON COVER. Fine entire Glasgow to Malta with a fine 6d deep lilac pl.5 (SG96) lettered TC tied fine strike of the very scarce "GLASGOW/159" barrel type duplex AU 14 68. Back stamped MALTA AU 20 68. The "barrel type" so called because the barred section is truncated and in the shape of a barrel. (Ref 107579).