Jacques Koerpel
Jacques Koerpel was the philatelic advisor to the Republic of Liberia in the 1940s.
Reportedly, a large number of his 1941 First Flight Surcharges covers were sold during a 1944 at H.R. Harmer Auction. [1]
References
1. "Modern Air Mail Covers Bring Good Prices at H.R. Harmer Sale" / p. 6 / The Airpost Journal / Oct 1944 / v.16 no.1