1911 FIRST U.K. AERIAL POST COLOUR TRIAL OR PROOF IN PALE YELLOW-GREEN ENVELOPE POSTALLY USED FROM WINDSOR TO UPPINGHAM. A good example of a colour trial or proof of the London envelope in pale yellow-green postally used from Windsor to 'Harry Clarke Esq., Lyddington, Nr. Uppingham,' (Rutland) with KGV 1d Downey cancelled superb strike 'FIRST UNITED KINGDOM/AERIAL POST/WINDSOR' date stamp SP 16 1911 Die 2. Slight creasing and slight damage from opening. This event was so popular that the official stationery sold out immediately and the organisers permitted the use of such items as colour trials. VERY RARE and price reflects imperfections. (Ref 141285).
