Martin Rich ) gurgled happily, sounding much like
they were saying :

They were, but they were number series that never got issued before
the annual suffix was introduced - so they've been kept (with others)
for issue to newly imported pre-63 vehicles or to pre-63 vehicles that
have somehow lost their original numbers.

http://fleetdata.co.uk/agerelated.html

I seem to remember (but can't find my sources) that this type of new
number issued to an old vehicle is specifically non-transferable, so
it can't be sold on as a 'cherished number'

That's the theory, but it seems to vary according to the person issuing the
number - the SSL number I've got on the Solex is not stated on the V5 as
non-transferable. Mind you, they've also managed to put it down as
"declared new at first registration" and "manufactured 1962",
simultaneously...

DVLA. Gotta love 'em.