South Africa Postage Due 1922 1d Multiple Offsets, Also Inverted

POSTAGE DUES: 1923 1d black & rose (SG D12var). Exceptional UM block of six with variety MULTIPLE OFFSETS, ALSO INVERTED of the value on the back of stamps, probably due to paperfold of sheet post-print (there is a gum bend which may attest to the cause). A spectacular block. See additional image below.