A removable clamp suitable for attachment to a structure, where the structure features a horizontal surface and two opposed, upright sides. The clamp comprises two relatively movable clamping portions 2, 4, with a first clamping portion 2 having a clamping face 6 for clamping against one of the upright sides of the structure, and a second clamping portion 4 having a clamping face 8 for clamping against the other of the upright sides of the structure. The clamping means exerts a clamping force against the upright sides of the structure. The first and/or the second portion has a mounting means 40 for mounting a post or other component on the clamp. Preferably the clamp features a guide means 16 to guide the movement of at least one of the clamping portions. A tongue 28 on one clamping portion 4 engages with a horizontal slot 26 on the other clamping portion to prevent twisting of the clamp in use. The invention may be applied to vertical plinths associated with bridges.
