I have a 1965 Jaguar S type - what type of number plate would have been fitted to it originally?
Would it have had pressed aluminium or would a higher end car of that era more likely had riveted letters, silver or white on black?
I always associated pressed aluminium with cheap cars and commercial vehicles.
Whilst I'm on the subject I always think black number plates look very odd on cars of the late sixties and early 70s.
Most bikes and cars post '68 had yellow and white. Certainly the ones I had did (they weren't new when I got them!) - which makes the black look out of place, more so on '70-'72
Contemporary film clips show the newer cars with reflective plates:
Villain (great film)