The cables are earthing or bonding, which is to do with the overhead 25 kV. I'm not sure whether it's strictly required in that position - the rules are quite complicated - or whether it's been done just in case.
It could be "drop zone protection" (drop zone is where the
OLE▸ catenary can fall should it come detached from its supports and anchors), the wire in the terminating planforms are likely to be fixed tension "trolley wire" so I suspect it is more likely to be anti trespass, and to prevent anyone climbing on the wall from getting within the touch distance of live OLE and pantographs