1900 6d on 3d Lilac & black with ERROR "MAFEK / 6d / BESIE", caused by a paper-fold during printing, tied to piece by crisp Mafeking MR 31 / 1900 cds, very fine and extremely rare, one of only 3 known of which this is the finest by far as the other two have faults, a rarity of Mafeking, cert. Brandon (1993) (Image)