No rules, no lined blocks
Setting 1A was 80-set printing and perforation, with extra pinning points below panes C & D and above E & F, as well as normal ones above panes A & B and below panes G & H.
Setting 1B was 160-set printing and perforation with pinning holes only above panes A & B and below panes G & H
160-set printing with added line blocks to reduce the possibility of ink deposits and being picked up by paper sag
320-set printing, with added continuous rules for the head and duty plate
With lined blocks, continuous rules and thin green and brown lines added to sheet margin between the left and right halves of the 320 Mill sheet. These distinctive markings only affect eight of the sixteen panes and only sixteen of the sixty four corners on the 320 mill sheet.
Setting 4A comes from a partial run of the 7th printing, issued 80-set (represents approximately 0.7% of the total print run of the 4d).
History: ex Ernest Good; ex Aureum (Stanley Gibbons, Feb 2016, £3’500)
Setting 4B is as setting 4A but with head duty rule cut away at corners
With thin lines removed
Setting 5a is as setting 4B but with thin lines between the two halves of the mill sheet removed, issued as 80-set sheets
Setting 5B is as setting 5A but 160-set with C & D panes joined to E & F panes