As those examples seem to show... the first 4 didgits of the number appear to have been gang-stamped and the last digit (and the L, etc) added by a gent named Nigel who was counting the hours 'til opening time at the local.
I assume the extra 'CTC's on 69123 are where Scott experimented with various stamps before making a new plate. Good idea. I practiced on a Coke can but that was rather thin to get a good feel for the effect of the hammer.