I know from the DVLC that my SP250 is a UK car but spent some time overseas with a change of number plate on it’s return on 1 March 1990.

I’ve now discovered a “California State Identifacation” plate in the engine bay with the #SP250103933.

Does anyone have any idea if I can trace from this how long it was there?

Many thanks

Roger

these I.D tags were most commonly used from mid 70s through early 90s and were issued by highway patrol. ( and still available today for cars with no existing vin plate ) reasons a little ambiguous, but generally it was down to the local DMV department requesting a 'new' id in order to register a car that was not in the Ca DMV system thereby requiring vin verification by police who often issued a new self adhesive tag if the existing vin plate was not present, held on with self tapping screws, or difficult to read.... Also common if car was 'lien sold' by a garage or towing company . Today with 'originality' being more important, more time is spent on research and there are more independant licensed and bonded vin verifiers who can provide a vin verification for DMV for a 'fee'. (commonly around $60 -$80 per car) Police are generally reluctant to do vin verifications today.. its both more convenient and easier to use an independent verifier. (talking the car to DMV for verification is often crapshoot as many DMV employees have little experience with classic cars and they often will refuse to inspect a car that is on a trailer or not running) however..if the vin plate is missing, Police inspection and issue of new ID is often the only way to get the car legally operable'.
in short answer... your car was most likely re-vinned in '1980s.. 'proof' of this would be hard and very time consuming to find..

Very many thanks for that

Roger