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).
Fitting of experimental raised crown pistons to a Wraith chassis to increase compression.
| Identifier | ExFiles\Box 148\1\ scan0187 | |
| Date | 9th August 1939 | |
| 1256 Rm.{William Robotham - Chief Engineer} Sr/VA.8/HB.{C. E. Harcombe} 9.8.39. re fitting Raised Crown (Experimental) Pistons to Wraith Chassis to increase the Compression file 1245 | ||