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).
Hand-drawn bar chart comparing the mileage performance of EXIDE and P&R batteries on a chassis before failure.
| Identifier | ExFiles\Box 54\2\ Scan088 | |
| Date | 4th May 1926 guessed | |
| EXIDE. P & R. {Sir Henry Royce} 15,544 miles. on chassis 2 cells failed Dismantled. 28,476 miles on chassis 2 cells failed Dismantled. | ||