DISRAELI DOCUMENTS
This leaflet refers, on its cover, refers to the 1939 models of the classic 'Le Cyclo' derailleur. For this reason I have guessed its date at 1939.
The derailleur range includes 2, 3, 4 and 5 speed variants, and it is possible that all these are also available in a lightwieght version with slotted tension pulley wheels.