Rubbing of a nameplate showing the number 51LB.
| Identifier | Morton\M21\ img055 | |
| Date | 8th February 1971 guessed | |
| PR ROLLS-ROYCE LTD LONDON & DERBY NO 51LB 51LB. | ||
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).