One of the first theatre houses in Paris was the “Salle des Machines” at the Tuileries royal palace. It was situated in between the “jardin des Tuileries” (Tuileries’ garden) and the “cour du Carrousel” (Carrousel courtyard/square). At the time, stage left and stage right were called “coté de la Reine” (Queen’s side) and “coté du Roi” (King’s side), actually referring to their boxes in the house ; “coté de la loge la Reine” (the Queen’s box side) and “coté de la loge du Roi” (the King’s box side).
After the French Revolution (1789) it was prohibited to talk about the royalty, so the 2 expressions became :
“coté cour” for stage left because the Queen’s box side was beside the “cour du Carrousel” (Carrousel courtyard/square) “cour” meaning courtyard, “coté” is side.
“coté jardin” for stage right the King’s box side was beside the “jardin des Tuileries” (Tuileries’ garden) – “jardin” meaning garden.
Many thanks to Fred Borzeix firstname.lastname@example.org for clearing that one up!
Fred has a French Glossary online at http://perso.numericable.fr/~fborzeix/fred.borzeix/spec/technic/info3glo/t_somair.htm