From the Rolls-Royce experimental archive: a quarter of a million communications from Rolls-Royce, 1906 to 1960's. Documents from the Sir Henry Royce Memorial Foundation (SHRMF).
That factory sirens and lights are to be used for A.R.P. purposes only, not for timekeeping.
| Identifier | ExFiles\Box 27\3\ Scan155 | |
| Date | 1st September 1939 | |
| To all Superintendents and Foremen 1204 Hs.{Lord Ernest Hives - Chair}4/T.1.9.39. Rm.{William Robotham - Chief Engineer} Factory Sirens and Lights. The Factory Bull, Sirens and Red Lights will be used only for A.R.P. Purposes, and not for time keeping. It therefore becomes the duty of the Foremen to see that the men are advised in some way from the Shop Clock when it is time to cease work. Hs.{Lord Ernest Hives - Chair} | ||