Following my last post on the forum I can now confirm that my car (J3474) has now been inspected by Dick Morbey and John Emmeett to whom I am very gratefulfor their considerable time.
As a result it is clear that the chassis was originally built as a J1 but the factory then decided to change it to a J2. Dick was able to confirm that the chassis and body left the factory as a complete car and John was able to point out the the chassis was drilled for the J1 rear footwell. I am hoping this will help me to reclaim the original registration number. Cheers, John Tinley