SIERRA LEONE 1991 OTTO LILIENTHAL GLIDING CENTENARY UNADOPTED DESIGN
180l Otto Lilienthal Gliding Centenary unadopted imperforate proof single prepared for the Anniversaries & Events issue of 20 December 1991. Affixed to thin card ex Questa presentation folder. Very scarce.
Note: similar designs were released 18 November 1991 for St Vincent, 9 December 1991 for Antigua & Barbuda, and 29 January 1992 for Maldives
