A security barrier post comprising: an underground footing (12;36;36a) comprising: a substantially vertical shaft (16;38) having a spring steel back plate (14;14a) and a spring steel foot plate (18;18a), both arranged substantially perpendicular to the shaft and extending to at least one side thereof, wherein, in use, the footing is at least partially buried; the back plate (14;14a) is attached to a rear facing side of the shaft, away from which an impact will occur, and is located at a position that, in use, is flush with or slightly below a surface in which the footing is buried, and the foot plate (18;18a) is located towards the lower end of the shaft, at a position vertically spaced from the back plate (14;14a), such that, under impact, the joints between the foot plate (18;18a) and the shaft (16;38) and between the back plate (14;14a) and the shaft (16;38), are in compression; and the security barrier post further comprising a barrier post (10;10a;10b) that extends, in use, above said surface, comprising a plurality of vertical spring steel elements, that are not joined together at their upper ends, aligned in the direction from the impact facing side of the shaft to the rear facing side of the shaft, away from which, in use, an impact will occur, such that, upon impact, the surfaces of the vertical spring steel elements can slide against one another. an underground footing (12;36;36a) comprising: a substantially vertical shaft (16;38) having a spring steel back plate (14;14a) and a spring steel foot plate (18;18a), both arranged substantially perpendicular to the shaft and extending to at least one side thereof, wherein, in use, the footing is at least partially buried; the back plate (14;14a) is attached to a rear facing side of the shaft, away from which an impact will occur, and is located at a position that, in use, is flush with or slightly below a surface in which the footing is buried, and the foot plate (18;18a) is located towards the lower end of the shaft, at a position vertically spaced from the back plate (14;14a), such that, under impact, the joints between the foot plate (18;18a) and the shaft (16;38) and between the back plate (14;14a) and the shaft (16;38), are in compression; and the security barrier post further comprising a barrier post (10;10a;10b) that extends, in use, above said surface, comprising a plurality of vertical spring steel elements, that are not joined together at their upper ends, aligned in the direction from the impact facing side of the shaft to the rear facing side of the shaft, away from which, in use, an impact will occur, such that, upon impact, the surfaces of the vertical spring steel elements can slide against one another. a substantially vertical shaft (16;38) having a spring steel back plate (14;14a) and a spring steel foot plate (18;18a), both arranged substantially perpendicular to the shaft and extending to at least one side thereof, wherein, in use, the footing is at least partially buried; the back plate (14;14a) is attached to a rear facing side of the shaft, away from which an impact will occur, and is located at a position that, in use, is flush with or slightly below a surface in which the footing is buried, and the foot plate (18;18a) is located towards the lower end of the shaft, at a position vertically spaced from the back plate (14;14a), such that, under impact, the joints between the foot plate (18;18a) and the shaft (16;38) and between the back plate (14;14a) and the shaft (16;38), are in compression; and the security barrier post further comprising a barrier post (10;10a;10b) that extends, in use, above said surface, comprising a plurality of vertical spring steel elements, that are not joined together at their upper ends, aligned in the direction from the impact facing side of the shaft to the rear facing side of the shaft, away from which, in use, an impact will occur, such that, upon impact, the surfaces of the vertical spring steel elements can slide against one another.