Persian Gulf. (Bahrain - United States). 1937. Air Mail envelope addressed to Bahrain bearing United States SG A630, 20c green and SG 720, 3c violet tied by 'El Segundo' date stamp 'Ap 19 37' endorsed 'via London, England' with Bahrain arrival '2nd May' on reverse. Nice item of incoming mail sent by Imperial Airways. Ex Proud.