Uncovered this when removing the rear seat from the Tourer today. Photos show the location and corrosion. It's a hollow tube containing what looks like a thin sheathed cable, part of a loom, and a rigid encased something-or-other, possibly a pipe or hose.
The round corroded tube is of quite thin metal. There isn't one on the other side so it wouldn't appear to be structural.
What is it please?