Gee
 

Forgotten the horrors of trying to count those b green lineswhilst trying to keep the grid lined up. Can't remember if you had to count two or three times for each slave. Different magnifications for tens and units.
Wasn't a back seater for Mk3, we sat side by side or nearly. My set was behind your head, so placed as one could get cramp adjusting in with ones left arm above shoulder hieght.