1911 FIRST OFFICIAL U.K. AERIAL POST, PROOF IN PALE YELLOW-GREEN OF LONDON ENVELOPE POSTALLY USED WINDSOR TO READING. A very fine London envelope PROOF IN PALE YELLOW-GREEN from Windsor to a Mr Gray in Reading with King Edward VII 1d scarlet tied fine large part strike 'FIRST UNITED KINGDOM/AERIAL POST WINDSOR' date stamp SP 16 1911 Die 2. Due to the success of this event the offical stationery sold very quickly and the organisers allowed the use of colour trials and proofs. Rare. (Ref 141482).
