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).
Melted 77°C sentinels for ignition coils on various GII models.
| Identifier | ExFiles\Box 45\4\ Scan206 | |
| Date | 22th September 1923 | |
| X. 4079- EFC2/T22.9.23. X.4079 - SENTINELS FOR IGNITION COILS. 77°C sentinels have melted twice on 3GII, once on 4GII, once on 6GII and once on 7-GII. EFC EFC. | ||