Well I might be premature in updating this thread but...
I never did find the parking sensor control module. Looked in boot, behind LH and RH boot trims, under seats, under bonnet, under dashboard etc. All difficult to access with horrible plastic clips etc.
Jaguar wiring diagrams didn't help as I found many that covered my year of car and all showed the module in different places - why the need to move it around so much? It's as if the installer changed stuff every day on the production line.
However I did notice a small water stain near the junction box (fuse box) rear on the RH side of the boot. I noticed the filler cap water vent pipe was blocked so unblocked it and not had the issue since. Maybe water was somehow getting into the boot and running through the fuse box causing the issue when it rained. Time will tell.