1941 10/- dull purple Robes (thick paper), 1/4 magenta KGVI, 6d brown Kookaburra (perf. 13½:14) and a pair of ½d orange Kangaroos (perf. 13½:14). Used on a registered, clipper cover from Windsor 9 DE 1941 to Manchester, UK.
The posting date is only a couple of days after the bombing of Pearl Harbour which saw most non-military aviation in the Pacific grounded. There is no indication that the letter did in fact fly the Pacific route to San Francisco, there is a manuscript endorsement on the back that it arrived in Manchester on 27 January 1942, some 49 days later. This would suggest that it was instead forwarded by sea.
BW(ACSC) Cat. # 178B + 202A + 211A + 214A