9 Sep. 1911 Specially Produced London to Windsor flight PC to London franked KGV ½d tied by double-ring "FIRST UNITED KINGDOM/AERIAL POST" d.s. and a 1918 square thin Pink card aerial leaflet to promote the 'DERBY TANK' fund raising and headed 'DROPPED FROM THE SKY/BY BRITISH AEROPLANES' and a rare survivor thus. (2) Cross Reference: DERBYSHIRE, MILITARY - WWI, AIRCRAFT, AIR MAIL COVERS (Image)