WALLIS BARNES: (1887-1979) English scientist & inventor of the bouncing bomb used in Operation Chastise (The Dambusters Raid) on 16th May 1943. Signed Royal Air Force Museum cover issued to commemorate Barnes Wallis and featuring a colour image of an R-100 airship and with an inset portrait of Wallis, post marked 15 th June 1976 on the 40 th Anniversary of the first flight of the Wellington bomber. Signed by Wallis in bold blue fountain pen ink with his name alone to a clear area. About EX

Composed of several subsidiaries, the Drouot Group is a major player in the art market. Hôtel Drouot, located in the heart of Paris, has been the world's largest public auction center since 1852. 15 salerooms are available to more than 70 auction houses. The emulation generated by an annual offer of 230,000 artworks from 21 major specialities - from Antiquity to street art - attracts some 3,000 visitors every day. The Group's digital platform, Drouot.com, offers digital sales - Live auctions (live broadcasting and participation in auctions), Online-only auctions (dematerialised auctions) and Buy Now sales (sales of lots at fixed prices). Nearly 2 million items are offered annually by 600 auction houses. Auction news is reported every week in La Gazette Drouot, the leading weekly magazine for the art market and culture published by Auctionspress.