Interesting anomaly.
As above lots of cars on transferring their old 3 letter 3 digit numbers were re registered on an A suffix plate, as was my Mk1 Mini but as it actually is a 1963 car it doesn't look out of place. Just wish it had its original "14 LAO".
We have a set of 4, L 444 *** prefix plates in our family with our initials, the certificate of retention clearly says that they cant be put on a car older than 1993/4 which is what the L prefix plates were issued to originally.
Auto numerology is interesting (well to me anyway, I'll get my anorak )