South Africa 1927 London 4d Progressive Die Proof, Endorsed

1927 London Pictorials 4d Native Kraal (SG 35b): Bradbury Wilkinson PROGRESSIVE DIE PROOF in brown on wove paper, mounted on presentation card (103x65mm) dated at upper right "Nov 2nd 27". The proof with blank cleared fields for the country name at top and "postage" at base. Marked in pencil manuscript at top "OK" with initials. Additionally endorsed in ink: "Darken", "Darken slightly on left.", "When submitting final proofs try to get colour still warmer. Initials. 1/11/27" A remarkable rare & exceptional proof in intermediate state.