1. A barrier having a plurality of elongate vertically extending supports which are respectively spaced apart from one another along a barrier line, the barrier comprising:a plurality of first mesh panels, wherein a respective first mesh panel is secured to and extends between a first support and an adjacent second support of the plurality of supports, the first mesh panels each having first and second vertically extending edges fixed respectively to the first and second supports and upper and lower horizontally extending edges, and
in respect of each of said plurality of first mesh panels, a respective deterrent structure fabricated separately from the first mesh panels, and opposing at least a part of each of the first mesh panels and secured to at least one of the plurality of first mesh panels, and the first and second supports,
wherein the first mesh panels each include a plurality of horizontally extending reinforcing formations vertically spaced apart from one another, wherein each formation is generally V- or U-shaped in cross-section, and
wherein the deterrent structure is positioned between an adjacent two of the horizontally extending reinforcing formations.