In the early 20th century Gabriel Hervier owned a bicycle business in Rive-de-Gier, near St-Étienne, France. In 1909 he is supposed to have patented a derailleur system somewhat similar to the Audouard design, with a fixed 'derailleur' and a sliding cassette of sprockets. Hervier's particular design uses a double cable mechainism to slide the sprocket cassette.
Gabriel Hervier put this system into production, offering his first bicycles for sale in, possibly, 1909 or 1910.
The only problem with this story is that I have yet to locate the patent (although Frank Berto shows drawing from it in 'The Dancing Chain'), and I have never seen any original literature produced by Hervier (although Frank Berto has a photo of a, rather tidy, Hervier bicycle).