I did a dating certificate for this bike in February 1998, probably for Mr Lemmon but I cannot be sure as my records are incomplete. The engine number was given as BK 897 rather than 497, which is a 1946 NG. The frame, XG 20758 is from a 1941 contract C10477 and was originally fitted with engine BH 11715.
Engine currently fitted BH 31379 is from a batch of unused numbers, which I assume come from engines supplied as spares as specified as part of most contracts but not listed in the despatch books. Crankcases supplied as spare parts were left blank, it was expected that the fitter would transfer the old number to the new cases and destroy the old, rarely happened in practise.
Roger Gwynn, Worldwide Membership Secretary, curator of the Machine Register and the works drawings