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).
Photograph of a broken spark plug, shown in two pieces.
| Identifier | ExFiles\Box 162\5\ img098 | |
| Date | 25th April 1939 guessed | |
| LG, FLR50X S, MADE IN, ENGLAND, B | ||