Your enquiry Rayna reminded me of the original 1823 lamps, two at each end of the suspension bridge. Superb cast iron sculptures that, albeit without their glass ball lampshades, actually survived the demolition and replacement by the 1920’s steel bridge but seem to have been ‘lost’ when the latest road bridge was built.
The two existing lamps at the north end of the bridge are poor replacements compared with the originals and a close up of them before they were removed shows low quality plastic balls with mock metalwork painted on them.
Perhaps the angle of the balls and the insubstantial curled metalwork supporting them seems to suggest that corrosion in the forty or so years since their erection had made them unsafe?