Sudan. 1931. Air Mail envelope headed 'Ibrahim Hamw, Port Sudan' addressed to 'Customs, Juba' bearing SG 48, 10m carmine and black (2) tied by Port Sudan date stamp '24th Mar 31' with 'Air Mail' label, sent by train to Khartoum with 'Khartoum - Port Sudan/ T.P.O. 2' date stamp '24/3', then by Imperial Airways with Sudan Air Mail/ Khartoum '26th March' on face, received at Juba with 'Sudan Air Mail/ Juba' dated '27th March' on reverse. A very nice item of the internal Air Mail service with scarce overprint stamps on cover.