Great Britain. (Isle Of Man). 1940. Official mail envelope headed 'On His Majesty's Service' addressed 'To The Commandant, Aliens Camps Headquarters, Castle Mona, Douglas, Isle of Man' cancelled by London/ Offcial Paid' slogan '20th July 40' with oval 'Direction of Military Intellingence/ War Office/ M. 1.1x' cachet in red on face dated '19th July 1940. Very fine and scarce.