I have just tackled an incoming message from one of our readers, who was looking to restore an original Blood Bank Marmite that they have, and he asked whether or not I knew what the small instructive text said. I was able to help them with the majority, and simply indicated that I surmised the final word was "EMPTY." They were able to confirm that this was indeed the case, since the only word that they could read of the original text was this one!
As a result, I can now confirm that the instructive text painted on the Blood Bank marmites is as follows:
TO BE USED ONLY
FOR WHOLE BLOOD
RETURN TO DESIGNATED
AIRFIELDS WITH RECIPIENT
SETS IMMEDIATELY WHEN EMPTY
I hope that this will help some of you trying to restore yours, and it means I can now complete the wording on mine, too!
Thanks for the help of everyone on this, a truly team effort indeed