1911 FIRST OFFICIAL U.K. AERIAL POST/"ROYAL AERO CLUB" ADVERTISEMENT. A very fine London post card in brown to Hampstead with KGV ½d Downey cancelled good to fine strike FIRST UNITED KINGDOM/AERIAL POST LONDON date stamp SP 9 1911 die 4. On reverse superb illustrated advert "1901 : TEN YEARS : 1911 : PROGRESS : With the Compliments of/F. HEDGES BUTLER/Founder of the/ROYAL AERO CLUB". (Ref 103279).