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).
Annotation on a drawing specifying the parameters for drilling six holes.
| Identifier | ExFiles\Box 90a\4\ Scan199 | |
| Date | 16th May 1936 guessed | |
| 9 6 HOLES EQUISPACED ON 2.375" P.C.D. FOR 3B.A. CLEARANCE 2750 | ||