Kilroy Danger Signal
Kilroy's Danger Signal was an automated system to detect and signal when the blast from one turret's guns might endanger the guns of another turret based on their present training and elevation angles.
When the system detected an unsafe firing condition, a loud audible alarm from a warning trumpet would sound in the endangering turret, and it was to be taken to mean, "Don't fire!" A visual indication would accompany the sound. 
It was widely deployed until the Iron Duke class inaugurated Kilroy's more assertive Danger Zone Fire Control system which locked the firing triggers when trouble was likely. The successor technology was probably used thereafter.[Inference]
- Annual Report of the Torpedo School, 1913. p. 103.
- Handbook for Fire Control Instruments, 1914. p. 53.
- Handbook for Fire Control Instruments, 1914, p. 59.
- Admiralty, Gunnery Branch (1914). Handbook for Fire Control Instruments, 1914. G. 01627/14. C.B. 1030. Copy 1235 at The National Archives. ADM 186/191.