Booklets
The first booklets of stamps were issued in October 1907 but they did not prove popular as the booklet cost more than the face value of the stamps it continued. Subsequently, up to the outbreak of war, the booklets employed advertising on the front cover to defray the cost of production. After the war booklets were not reintroduced until 1927 when a limited number were issued with advertising on the front cover. In the period 1930-32 advertising was included on the covers but also in stamp-sized labels the same size as the stamps and included in the same pane. These labels are known as timbres-publicité or "PUBS". The labels and stamps were printed together in sheets designed to be cut up by Post Office clerks and then made up into booklets by stapling through the selvedge. In the early days a complete sheet was sold in error and to avoid creating a rarity it was decided to sell complete sheets to anyone who wished to purchase one. Dealers and collectors subsequently broke up the sheets to provide tête bêche, interpanneaux tête bêche and stamp-publicity pairs. The stamps came from several definitive issues: “Houyoux” & “Kepi” [both King Albert 1st ], “Allégories” and “Lion héraldique” with a variety of commercial interests paying for the publicity “stamps”. The issue from 1936 to 1941 principally employed the “Petit sceau de l’Etat with higher values in the “Invalides” and “Col ouvert [both King Leopold III] definitive issues. Philatelic themed "PUBS" were commonly paired with the 35 centimes Petit sceau de l’Etat postage stamp.
This section of sheet shows how the various combinations of stamps and labels originate.
More modern booklets give rise to partially imperforate stamps, tête bêche, and se-tenant pairs.
Panes were completed with "PUBS" in the form of the post office emblem.
Booklets of commemorative stamps have been introduced often with attractive covers.
More recently booklets of self adhesive stamps have proved popular with a flower theme.