Corinphila Auction 291-297 Day 2

First UK Aerial Post London-Windsor Trade Advertisements 1911 (Sept. 9): Dark brown card (first printing, plate 23) without imprint on address side, franked with King George V ½ d. green cancelled by "FIRST UNITED KINGDOM/AERIAL POST LONDON SP 9" to Belfast. Plain back as to be sold for advertisement spaces, but used for private message.