SOUTH AFRICA → CANADA registered airmail cover to Canada with Pretoria 4 Mar 1942 datestamps, airmail and registration labels and “RETURN TO SENDER” cachet on front.  Myriad of datestamps on back that include Ottawa, New York and Cape Town (arrival datestamp of 10 Sep 1942) plus “Dead Letter Office” cachet from Ottawa of 26 Jun 1942.