Jack, glad to know it wasn't because in the 80's we were all oiks lacking Mog's and JE's social connections.
For what little it's worth mine was C0 or CO (never been quite sure) followed by five numbers and a letter.
Computerised pay accounts reminds me of bring told by the relevant pusser shortly after arrival at BRNC, that if I moved my account to N?????t's Dartmouth branch I would be paid a day earlier.