 Stamp booklets were first put on sale on 21 August 1931 . Booklet construction was a lightweight cardboard cover stitched on the left @-@ hand side with panes of stamps ( usually four panes ) , advertising panes and <unk> bound in . Until 1956 most booklets had half of the front cover devoted to advertising , and until 1963 booklets also had serial numbers on the front cover : two numbers indicated the year of issue and serial number ( in that order on the early issues but with the order reversed for later issues ) , until 1963 when the serial numbers ceased . Since 1983 , most booklets are no longer stitched ; the stamp pane , or panes , are glued into a folded card cover . 
