South Africa 1931 (24 AUG.) 1st flight Reg. Grootfontein to Keetmanshoop to  bearing  4d 'air' adhesive of South Africa overprinted S.W.A. - Large type (SG 72) block of 4  and 2d (SG76) pair all tied by black rubber LUGPOS/KEETMANSHOOP/AIR MAIL handstampand ,  and date cds. transit and AUG 26 arrival cds on back.