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).
Drawing comparing the present and proposed design for a small knob or cap.
| Identifier | ExFiles\Box 69\3\ scan0029 | |
| Date | 19th January 1925 guessed | |
| PRESENT PROPOSED SCALE FULL SIZE 1" of blued or oxidised steel as small as possible of metal blacked similar to rest of control head | ||