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).
Confirming the engine type used by Campbell was the 1931 No. R.39.
| Identifier | ExFiles\Box 142\1\ scan0003 | |
| Date | 5th October 1937 | |
| 1204 Sg.{Arthur F. Sidgreaves - MD} from Rm{William Robotham - Chief Engineer}/Gry.{Shadwell Grylls} Rm{William Robotham - Chief Engineer}/Gry{Shadwell Grylls}12/R.5.10.37. Replying to Sg{Arthur F. Sidgreaves - MD}9/E4.10.37., the man who was with Campbell is out of England, but his department assures me that the engine used was the 1931 type, No. R.39, and that this was last tested in these Works in December 1932. Rm{William Robotham - Chief Engineer}/Gry.{Shadwell Grylls} | ||