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).
Family tree diagram of battery ignition and coil part numbers.
| Identifier | ExFiles\Box 37\1\ scan 177 | |
| Date | 17th February 1930 guessed | |
| X3199. X.3199 - TREE OF BATTERY IGNITION AND COIL NUMBERS Battery ignition (general) X.3199. R.R. trembler ignition (chassis) X.1520 R.R. non-trembler ignition (chassis) X.3129. R.R.non-trembler ignition (aero) X.3173. Trembler coils (general) X.243. Non-trembler coils (general) X.918 R.R.trembler coils X.562. R.R. Non-trembler coils X.3445 | ||