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).
Conclusion of tests recommending the standardization of Champion and Mercury spark plugs for U.S.A. and English made cars respectively.
| Identifier | ExFiles\Box 49\5\ Scan090 | |
| Date | 16th February 1921 | |
| Contd. -2- R1/G16.2.21. satisfactory. In conclusion, I agree (subject to further exhaustive tests confirming) to prepare for at once standardizing the Champion (Canadian make) for U.S.A. and the Mercury (Birmingham make) for English made cars. R. {Sir Henry Royce} | ||