weird question, primarily during covid, i remember seeing the dispatchers at leeds station using a kind of device that made a whistle like noice, like a high pitched shrill?
does anyone know what the name of this thing is? i feel like i managed to find it at the time, and i just cannot remember what i searched for.
does anyone know what the name of this thing is? i feel like i managed to find it at the time, and i just cannot remember what i searched for.