Great detective work! hard yakka, was how slogging work came to be known. The still existing brand of work clothing is "Yakka"
Reminds me;when arriving in Canada from US,by rail.Vancouver I think. Customs checked ID,bags etc. Then gave hard looks. Is there something wrong,I says. Him: Yes,you're Aussies...Where's your booze? All Aussies are carrying alcohol! Good laughs all round. sadly those days are dying.