no plates with NNN AAA where N is numeric where issued in the mid 50s /QUOTE]
For accuracy, I've had 4 cars, 1961 to 1964 which were all NNN AAA.
I sold two of their plates and DVLA issued their non-transferable replacements, AAA NNN and a new-fangled 'B reg'. RAS 220 went down a storm with the local weed dealers, when I lived in SW2.
Before The DVLC and V5s existed, mid-1970's vehicle registrations were done by county councils, so there was a lot of variation,
E.g. one could randomly get a 1 letter 4 digit (A NNNN) even up until 1964, as they used up unallocated marks.
Top Marques may well have had those offered first, I think.