Not being that familiar with Putney Bridge I have no idea but the list in the link I provided clearly indicates the presence of cctv on Putney Bridge. I expect the most likely location is either end. Other bridge related cctv cameras listed for Wandsworth, the borough in which Putney is located...
Why not cctv on a bridge? There are plenty of other council run cctv cameras in that location including on that bridge (see camera 601 on this link). As you will see that area is saturated with cctv. He must have been captured countless times even after leaving the bridge so I think there is a...
Given this occurred in London he must surely have been captured on some other cctv which identifies him more clearly. If so at least a still from that cctv footage should be released to help with identification.