Registers of Certificates of Competency of engineers kept by the Registrar General of Shipping and Seamen and its predecessor.
Registers covering certificate numbers 39000-58999 are to be found at the National Maritime Museum under references:
RSS/ENG/1 1902-1905 39000-43999
RSS/ENG/2 1905-1909 44000-48999
RSS/ENG/3 1909-1913 49000-53999
RSS/ENG/4 1913-1918 54000-58999