Natal 1858 4d Cape Triangular Franking, Early Ocean Mail Rate

1858 COASTAL OCEAN SERVICE CAPE to NATAL: Neat small format envelope from Cape Town (VF unlined backstamp cds MY 29 in red) to "H Wathen Esq / Pieter Maritzburg / Port Natal". Franked 4d Triangular (deep blue, SG 6, full margins two sides, cut-in evenly along base) tied by neat triangular defacer. Blue crowned Natal (1 JU) arrival mark reflecting a delivery time of only 4 days. VF, an uncommon early ocean mail item at the then-prevailing 4d rate to Natal. Ex Bill Hart & Dillaway. See additional image.