PS1    1   Filler             Green-grey
PS2    4   Filler             Brown
PS9    50 Filler             Slate Grey
"The 1f, 4f and 50f stamps may not have been officially issued, although I saw and examined some about 1956, and found the overprints to be genuine, If those were unauthorised, as they now seem to have been, they nevertheless have been struck with the original handstamp allegedly destroyed shortly after use. "
F. Konrad              "The American Philatelist" Nov 1981   

Ten copies of the Red Cross 30+30 and 50+50 were also overprinted, but never sold at the PO, and are comsidered proofs.