Between 1889 and 1936 the Portuguese government supplied the Red Cross (Cruz Vermelha) with stamps for franking their mail. Many issues are overprinted Porte franco with a cross. Other agencies that received franking privileges before they were withdrawn in 1938 included civilian rifle clubs, the Geographical Society of Lisbon and the National Aid Society for Consumptives.
1931 Franchise Stamps for the Red Cross
The Camoens issue of 1924 was overprinted in 1931
with the years "1931" and "1932" on different values.