Air Mail cover 1919 (12 April) unfranked O.H.M.S. envelope (vertical folds) flown on the Alexandria - Kantara round trip, showing a superb strike of the framed straight line "AERIAL POST/E.E.F." h.s. in black, with despatch "ARMY POST OFFICE/SZ 4" skeleton type c.d.s. as well as "BASE ARMY POST OFFICE/Z" c.d.s. (13 and 15 April). Photo