|The 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 milliemes (equal to 2d).