Auction #96 Worldwide Air Post Stamps and Postal History, Philatelic Rarities of the World

1938, large die proof of 20c in dark carmine, imprint ''Special Delivery'' and ''X-G-673'' at bottom, proof size 107x85mm, printed on India paper and mounted on slightly enlarged card with protective paper at top, negligible soiling spots at bottom left and top right, no gum as produced, VF and rare, NSSC SD 7dp2, C.v. US $2,000, Est. $1,000-$1,500