Hello GraphiteGhost - thank you for your input.

These 2 are stuck (tight) to the windscreen. They don't swivel or move at all.

Please ignore the thick lead you see that goes infront of the rear view mirror mount, that's coming from my Dashcam.

The wiring for these 2 (questionable) "sensors" must go up behind the roof lining, as there is no physical wiring I see coming out of them anywhere else.
Plus if they were for an aftermarket alarm system, when I bought the car, I got no extra documentation, or additional aftermarket alarm fobs, that would confirm that to be the case. The plot thickens!

Good point on the Service manual, I will look into that - if further details are mentioned on how the UK / European alarm system is integrated (if at all)...
No UK Crossfire owners have yet chimed in, to say if they also have these in theirs (or not).