So, I confess I had to ask around about this! And, having been pointed in the right direction, I discovered teh cable is indeed shown in the AIM, but nowhere near the section I expected it to be!
It apparently is a reinforcement cable, designed to hold the front "clip" in place in the case of an accident! So, the loose end in your photo John, should be attached to a reinforcement plate, that would normally be hidden I think behind the plastic "debris screen" at the ends of teh wiper tray.
Anyway, the relevant page of the AIM is attached.....
