There are three recognized models of the Sunbeam motorcycles manufactured by BSA between 1946 and 1957. Trying to determine whether a Sunbeam is 'as it left the factory' or in 'concourse' condition is an inexact pass-time for the reasons detailed below. However the model pages list the standard differences which can aid identification.
The Sunbeams were produced in an age when 'production line' style manufacturing was not as uniform a process as it is today. Nowadays all motor manufacturing tends to produce identical homogonised vehicles, but that simply was not the case with Sunbeams. Distinctive differences exist between the models and early and later bikes, however if the factory had run out of 'improved' or standard pieces then other 'old' or 'wrong' parts may have been fitted in the factory. These cases may have involved fitting any available parts, whether they came form the same model or not. Additionally many Sunbeams had production modification retrospectively fitted to older bikes to help retailers sell them.
Because the bikes are all now more than fifty years old, all but a very few machines will have been altered or improved during their lifetime, especially those being ridden and used.