Can anybody tell me whatever module this is it is located behind the rear bumper with a wire going to the front of the car.

 

Are there no Jaguar product codes on it or does the connected wiring lead to a designation?
As far as I know, apart from the (optional) parking sensors, there are no other modules in the rear bumper.

It may be a crash impact sensor or an aftermarket theft detection system that some insurers require. That cable that I see in the photo, looks very much like the connector that comes with it.

At the moment I am dismantling an X308 (3.2). I'll let you know if I find something similar in the rear bumper.

 

Could be an old front and rear radar detector?? I don’t think it’s factory because of the screws.

 

It could be a very old toll tag...they used to be fitted right behind the bumper or grill in the 90's, early 2000's.

 

It should have some sort of manufacturing number on it, either stamped or a label or some sort.
Without either of these, there are a mountain of possibilities that only an internal inspection will
reveal.