Natal 1874 QV 6d Die Proof Before Hardening, ex DLR Bunhill Row

1874-99 DIE PROOF for the QV 6d (SG 70 etc) in black on glazed card dated Oct 3 1873 and marked BEFORE HARDENING. VF example. Barest suggestion smoke soiling at very edges (more definitively on everse) source this proof to that known group of Natal die proofs originally salvaged from the 1940 bombing of De La Rue's Bunhill Row works (which were destroyed in the ensuing fire). Rare & attractive. Ex De La Rue archives.