They used to register cars on the year they were imported not the year they were manufactured. This was imported into the UK in August 1975 hence the 'P' registration. It could be give an age related number but it doesn't bother me so I never bothered, it would also lose some its history then by being on a different number. Interestingly I came across a photo of this car parked outside Corvette Kingdom in the late 1970s, which was quite cool. Had the number been changed that would have gotten missed.