Naafi Postal Seal used on front of a postcard contrary to regulations
Army stamps were for use only through military channels.
The cover here has been posted into a normal civilian postbox, hence
the postmark of Ismailia Camp.
It therefore then received the 'O' marking showing that the stamp was invalid for use.
Subsequently it then received the boxed
[T] in Egypt and a postage due stamp in England for 4d, double the postage rate of 10 millièmes (equal to 2d).
The small 3 millièmes stamp was brought out for the concessionary rate for Christmas in October 1940.
However free postage was
implemented soon after, making its use redundant: only a few covers were posted early, making its genuine on cover quite rare.