South Africa 1928 OHMS stampless env OFFICIAL REGISTRATION label RARE

1928 South Africa OHMS stampless envelope with OFFICIAL REGISTRATION blue label affixed PRETORIA 13 DEC 28 postmark RARE – a directive dated 25.5.1926 stated these labels were to be used on registered articles NOT CONTAINING CASH instead of the usual blue lines apparently in use from 1.6.1926