Does anyone have the details of the additional parts required for surround view? I don’t want to retrofit it but I am interested in how it is connected to and selected in the head unit.
Is there a separate control module for instance or is it just a case of the additional cameras being connected to pre-existing inputs on the head unit and then being enabled in software somehow?
This is just idle curiosity at this point  2011 TDV8 4.4 Vogue SE in Galway Green with Black leather
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I suspect there is an additional module.
I have it and on IId tool it states without rear view camera.

So I assume it all runs through separate unit.

It's a Module under the left seat, at least in LHD models.
All cammeras are connected into this module.