Siroco is a slightly mysterious brand. It is mentioned in 'The Dancing Chain' and in several places on the internet (often spelled with an extra letter 'c' here or there). But it is hard to get a grip on.

What I do know is:

• Siroco products are described in three French patents. A rod operated derailleur is described in one patent applied for in 1940. A cable operated derailleur and its lever are described in two further patents applied for in 1942.
• The two patents for the derailleurs are in the name of Antionette Vialette née Chevillard. The patent for the lever is in the name of Jean Vialette. They seem to be a husband and wife team.
• The patents were registered in Saint-Étienne - so the company may have been based there or thereabouts. I have also seen a photo of a Siroco box which, according to the printers mark, was printed in Saint-Étienne.
• You do see both the derailleurs around occasionally - so they may have been made in some numbers. They are manufactured to a respectable level of accuracy and overall quality.
• Err, that's it.