War time conditions made it imperative that stocks of paper be conserved
and as sales of the
1940 Health stamps had
been around 60 percent of the
1939 Health
stamps the usual practice of destroying unsold stamps once the issue was
withdrawn was considered wasteful. Instead the remaining stamps plus a
small supplementary printing were overprinted 1941 - just so that the 1941
issue could be distinguished from the 1940 issue. There are slight
differences in the intensity of the coloured inks used between the two
printings with the stamps printed in 1941 having a deeper colour.