Sudan. 1940. Registered Air Mail envelope addressed to Cairo bearing Sudan SG 44b, 3p red-brown and blue (3) and SG 44, 4p ultramarine and black (block of eight) tied by oval Khartoum date stamp p'23rd Feb 40' with matching registration label and 'Sudan Censorship' label in green tied by triangular 'Passed/ Censor/Sudan/ 3' on face and reverse with Cairo arrival. Very attractive franking.