These started on the 1977 base with number 1A*A1.
It appears that they went up to 9E*Z9 (or something close) and then the series changed
and restarted at A1*1A - but still on the 1977 (tan) base.
1977 BASE
1977 BASE
1977 BASE

1979 BASE

Only samples were issued on the 79 base.
The tan base was issued up until 1992 - there were no blue plates issued except samples.
The numbering on the tan base went as high as M9*9R.
The 1992 graphic base started at N1*1A.
1992 SAMPLE

1992 REMAKE

1992 REMAKE

David Doernberg - 1825
1992

David Doernberg - 1825
c.1997
c.1997
2003

Is this the first use of a "Q"
on a standard-issue plate ?
Kevin Halfpenny - 9069
2004 AVERY SAMPLE
2004 AVERY BASE

2005
2005 REMAKE

Remake of 1978 base
2005
In 2008 Z9*9Z was reached, and the numbering continued where it was left off
with the original 1977 base plates - this might be 1F*A1.