Theatre history teems with legends and superstitions of actions that bring bad luck on an actor. Forgetting to leave a light on in an empty stage after a performance can summon an angry ghost of Thespis. Receiving flowers before a show rather than after a curtain call can lead to a lackluster performance. Mentioning the name of Shakespeare’s “Scottish play” in a theatre spells doom.
Whistling on stage is particularly unlucky, and the roots of this date back at least to the 17th century. Before stage managers, there were prompters who created the acting version of a playscript, assigned the roles for a stock company of actors, oversaw rehearsals, ensured the actors were in their correct places to make their stage entrances, and cued music, special effects, and scene changes.
In the days before electricity, prompters standing backstage cued scene changes by whistling or ringing bells. Speculation suggests the practice was borrowed from nautical traditions of whistling on ships and docks to raise and lower sails and cranes. The theatre season coincided with the cold winter months when the shipping trade slowed. Sailors and dockworkers could sometimes get jobs as stagehands, where they knew how to handle ropes and rigging systems and how to repair rips in canvas backdrops.
Promptbooks from the Restoration through the late 19th century often include “W”s for “whistle” to mark a scene change. The whistle could be heard by the audience, but was an understood convention of the time that didn’t seem to detract from the experience of watching a play. In particularly dramatic scenes, some prompters may have used a silent cue, holding up the appropriate number of fingers to indicate which backdrop or curtain to change.
Understandably, a moratorium against whistling on stage ensured the prompter’s whistle would be understood without confusion. An innocent actor inadvertently whistling in the wings might send a backdrop flying in too soon and cause an accident.
Whistles were replaced by electric light cue systems and then intercoms in many theatres at the turn of the century, but the caution to avoid whistling on stage remains.