All that can presently (July 2019) be gleaned from sheet music covers and by internet searching is that Léon Dequin is the one-off composer of Le Vrai Cake Walk (1906).
Surfers are welcome to contribute information about this composer.
This list is arranged in chronological order and contains 3 works by Léon Dequin.
It does not claim to be complete and represents only the number of items located. Keys: