Air Mail cover 1926 (15 Jan.) R.A.F. Goodwill Training Flight Khartoum - Cairo return flight envelope, unfranked and showing unframed "By Return of/Special Flight/Cairo to Khartoum" h.s. in violet together with similar "Khartoum. 15 1926" despatch and "17 Jan 1926" straight line arrival d.s. Fine. One of only 35 flown covers.