Abstract: The present invention relates to a structural support post (1) for use in a partition system (2) for supporting one or more panels (6) having panel support brackets (25) with hooks (44) at or in the vicinity of edges of the panel. The post (1) comprises a profile tube having a diameter of at least 70 mm and a multiplicity of angularly spaced longitudinal undercut slots (13), the walls of the slots being provided with insert plates (24) formed and arranged for engagement by hooks (44) provided on the panel support brackets (25). The support posts (1) may provide, in use, a substantially secure support for a security partitioning system (2).