Smythe's Private Study Monitor Dial (Concealed Visual Telephone Control)

The hidden monitor’s dial is the precise control mechanism that Smythe uses to activate his secret communication line. Its turning is a deliberate, almost ritualistic act, symbolizing Smythe’s shift from public military figure to private conspirator. The monitor itself becomes a window into his true objectives, its activation accompanied by his clinical request for 'five thousand specimens.' This object is the narrative device that propels the story forward, revealing Smythe’s allegiance to something beyond the war and hinting at a larger, non-human operation.

The concealed visual telephone monitor is the device Smythe uses to communicate with the unseen controllers. Though not explicitly visible in this event (as Smythe has already terminated the transmission and closed the portrait over it), its presence is implied as the catalyst for Smythe’s urgency to leave. The monitor serves as a critical link to the higher authority overseeing his experiments, and its covert nature underscores the secrecy of his operations. Its role here is to drive Smythe’s need to escape and cover his tracks, ensuring no trace of his true allegiance remains.

The ‘video screen’—a concealed visual telephone monitor hidden behind a portrait in Smythe’s room—is the linchpin of this event, though it’s only referenced indirectly. Its existence is the Doctor’s bargaining chip, the proof Carstairs demands to overcome his skepticism. Zoe’s failed attempt to explain it underscores its alien nature in 1917, while the Doctor’s insistence on showing it to Carstairs frames it as the key to unmasking Smythe’s temporal manipulations. The screen’s absence in the wine cellar forces the Doctor to pivot to action, making the object a catalyst for the alliance’s formation.

The concealed visual telephone monitor is the linchpin of this event, serving as tangible proof of Smythe’s manipulation of the war game. Initially invisible to Carstairs and Buckingham, the monitor only becomes perceptible after the Doctor urges them to concentrate, revealing its function as a 'visual telephone'—a device that combines audio and video communication. Zoe’s technical insight identifies it as a tool linking Smythe to unseen adversaries, exposing his role as a puppet master. The monitor’s existence shifts the dynamic from suspicion to active defiance, as the officers now have undeniable evidence of Smythe’s betrayal. Its revelation is a turning point, validating the Doctor’s warnings and setting the stage for the group’s resistance.