There is wire under the bridge - having wire there was never the problem.
The issue is that to get through the bridge, but then be high enough over the virtually adjacent level crossing, the gradient of the wire relative to the track was extreme - way beyond the system design limits for UKS1 OHLE.
Very steep relative wire gradient is a problem as either - the pan can’t react fast enough and becomes detached from the wires; or in the opposite direction suffers too much compression force and suffers damage.
Simulation and Modelling initially suggested 60mph was the maximum “safe” speed at that wire gradient, and so an EMU60/125 speed limit was installed under the bridge. As IETs could go significantly faster on diesel they were doing changeover, while the 387 ECS moves to Cocklebury EMU Sidings crawled under the bridge. Further modelling and some verification runs showed that if all parties accepted a higher degree of wear to some components 110mph would be possible. Hitachi, GWR and Network Rail agreed and so the speed limit was increased to 110 for all trains under the bridge, and changeover equipment removed for use elsewhere.