1950 Triumph speed twin frame number

Hi Smiffy, you say your Father's machine is a 1950 350 Speed Twin, this poses a small dilemma, the Speed Twin is 500cc not 350, from 1950 to 1962 the frame and engine umbers matched, engine numbers were prefixed with the model (eg 3T-1001N), all Pre Unit 500 and 650 Twins from 1950 started from number 1001N to 16085N - November 1949 to October 1950 and 1951 are 101NA to 15808NA - November 1950 to October 1951. Looking at your engine number should also correspond to the frame number. The 350 is the 3T series, the first year for the 3T was 1946 that being the 3T in 1947 out came the 3T Deluxe, then the Twenty One, 3TA Twenty One, sprung hub, bathtub etc etc. It may well be that either the frame or engine have been changed at some point in its life, if you take and upload a picture of the engine number, and a separate one of the frame, i.e. complete bike I may be able to shed a little more light on things. In theory from what you say you should have a 1950 3T 350 ohv. Do you have the original buff log book with the frame and engine numbers on, also when people changed either the frame or engine back in the day they often did not notify a change. The frame number should be stamped on the headstock (near side) in front of the petrol tank. If you are restoring the bike then I guess you will be stripping the frame to bare metal before repainting, this may well show the frame numbers, although I strongly suspect not, your Father may have even bought the machine as it is now, not realising it had a change of engine or frame.