A support post assembly (10, 210) for supporting a fall safety line, the support post assembly comprising: - a support post having opposite first and second ends (33, 34), an axis extending between said ends, and at said first end, a base portion for fixing the assembly to a supporting surface; - a safety line mount (14, 214) to which a safety line may be secured, the safety line mount extending away from the second end of the support post; and - a shock absorber housed within the support post between said first and second ends (33, 34), the shock absorber comprising a pivot (20, 22), such that in the event of a fall by a worker secured to said safety line, lateral forces imparted to the safety line mount (14, 214) by the fall are transmitted to the shock absorber thereby causing the shock absorber to deflect laterally with respect to said axis, wherein the pivot (20, 22) is connected to the base portion and located between said first and second ends (33, 34) of the support post, the shock absorber having a first portion and a second portion and said first and second portions of the shock absorber being located on, respectively, opposite first and second sides (52, 52a) of the pivot, said lateral deflection causing at least a part of both said first and second portions (40, 40a) to rotate about the pivot (20, 22) so that both said first and second portions of the shock absorber absorb energy from the fall, characterized in that said first and second portions of the shock absorber are, respectively, a first resilient block and a second resilient block, and wherein deformation of each resilient block absorbs said energy from the fall. - a support post having opposite first and second ends (33, 34), an axis extending between said ends, and at said first end, a base portion for fixing the assembly to a supporting surface; - a safety line mount (14, 214) to which a safety line may be secured, the safety line mount extending away from the second end of the support post; and - a shock absorber housed within the support post between said first and second ends (33, 34), the shock absorber comprising a pivot (20, 22), such that in the event of a fall by a worker secured to said safety line, lateral forces imparted to the safety line mount (14, 214) by the fall are transmitted to the shock absorber thereby causing the shock absorber to deflect laterally with respect to said axis, wherein the pivot (20, 22) is connected to the base portion and located between said first and second ends (33, 34) of the support post, the shock absorber having a first portion and a second portion and said first and second portions of the shock absorber being located on, respectively, opposite first and second sides (52, 52a) of the pivot, said lateral deflection causing at least a part of both said first and second portions (40, 40a) to rotate about the pivot (20, 22) so that both said first and second portions of the shock absorber absorb energy from the fall, characterized in that said first and second portions of the shock absorber are, respectively, a first resilient block and a second resilient block, and wherein deformation of each resilient block absorbs said energy from the fall.