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).
From GWH to Mr. Hives detailing the results of testing M type and D type forward sparking plugs.
| Identifier | ExFiles\Box 33\3\ Scan230 | |
| Date | 12th October 1922 | |
| Mr. Hives from GWH.{George W. Hancock - Head Chateauroux} *3780 818/2C. 12.10.22. Roy{Sir Henry Royce}/MS4/PD29.9.22. RE. FORWARD SPARKING PLUGS. We have tested these plugs on 49-GB and 6.EX Cars. The Mica plugs (M type) have failed in pocket position on 6.EX. The D.{John DeLooze - Company Secretary} type we are continuing to run - they appear to be O.K. as far as tested. GWH.{George W. Hancock - Head Chateauroux} | ||