Belgian Customs Seal, Image & Found by Barry Norris.
Found on Essex/Hertfordshire border.
Dia.= 20mm Thickness = 6mm Weight = 17g
One side has the lion rampant on a crowned shield from the Royal Belgium coat of arms as of 1837 (this is the 'lesser arms' used by the Government) with ROYAUME DE BELGIQUE circling it. On the other side is ANVERS which is French for Antwerp curved above the number 33 and (ENTREPOT) curved below. Entrepot (originally a French word for warehouse) is now used as a term to signify a customs area.
Around the edge is the word DOUANES which is French and Dutch (satisfying both the main languages of Belgium!) for border control customs.