Mafeking Siege 1900 SG13 6d on 2d Green & Carmine F/M with Cert

1900 6d on 2d green & carmine of Bechuanaland Protectorate, Type 2 Overprint (SG 13). F/M large part OG example, nicely centered, a scarce stamp mint. Photo-cert: Eichele BPB "A well centred stamp with fresh colours. Only 1200 printed.". (cv£1600).