Australia 1966-73 deep blue error, SG386cbAustralia 1966 73 5c deep blue error, SG386cb. Upper left corner block of 6 (3x2), comprising two horizontal strips of three, each with the left pair ERROR IMPERFORATE. Exceptional quality, unmounted mint with full original gum. A spectacular modern rarity, especially desirable and important in this attractive positional form. Only 20 strips existed, from two sheets discovered. These were the first stamps issued following the decimalisation of