1866 (Dec 3) envelope from Panama to France with an exceptional four-color mixed franking with French Empire perf. 20c blue Y&T 22 and Great Britain 1862-64 6d (hair lines), 1865-67 3d pl.4 and 1864-79 1d red pl.88, each tied by anchor diamond cancellation with maritime postmark "PANAMA PAQ. FR. A N°1" adjacent, "AFRANCHISSEMENT INSUFFISANT" mark and "10" due hs below, reverse with Paris and Cauvigny arrival, small portion of backflap missing, a unique mixed franking of GB and France from the French ship mail in Panama, with an extremely attractive visual appeal; signed Baudot and Scheller, cert. Calves (2016) and Scheller (2015). (Image)