Great Britain. (French Indo-China - Postage Dues). 1906. Mourning envelope addressed to Haiphong, Tonkin, Cochinchina bearing Great Britain KEVII SG 230, 2 1/2d ultramarine tied by West Brompton double ring '9th Aug 06', routed via Saigon, underpaid with framed 'T/ L' hand-stamp (applied in London) and bearing French Indo-China "Grasset" SG 33, 5c green mixed with French General Colonies postage dues Yvert 7, 15c black (imperf x 3) tied by Doson/ Cochinchina receiver '2nd Sept'.
Very rare combination from Great Britain with usage of French Indo-China paying the postage due as the 5 cent French General Colony had not been supplied to the small town of Doson.