1921 UNDERPAID MAIL SWITZERLAND TO LONDON. Post card Champex to London with Swiss stamp on illustrated side of post card and cancelled CHAMPEX 29 VIII 21., and surcharged due to stamp on wrong side of envelope. Large "T" Swiss tax mark, London "2D/F.B." charge mark and 2d postage due cancelled MUSWELL HILL 31 AU 21. (Ref 105270).