Saint Helena 1919 War Tax Stamp Franking on Letter to SA

1919 Eastern Telegraph Company envelope to Durban, South Africa, registered, franked 3 x KGV 1d WAR TAX stamps (BOTH TYPES, SG 87&88) tied by three strikes of departure cds JY 18. Front bears St Helena registration label No 73, relevant arrival mark Durban 6 AUG on reverse. F-VF, minimal light spotting, scarce stamps on correctly rated commercial cover.