South Africa 1932, group of 4 registered airmail covers posted January 26-28 1932 from different towns: Kimberly; Capetown ; Pietersburg; and West Victoria. 3 posted to London and one to Calcutta. All properly franked with the new (Jan 26) flat rate for airmail, Sc #C5-6 (1929) 4p & 1sh Air Post Set. 
Early 1932 it was announced that with effect 27 January 1932, the Air Mail rate within the Union wouldbecome an inclusive fee of 4d per half-ounce. Further that Air Mail stamps would be valid for allpostage requirements, including the prepayment of parcels and registration fees.