Hiya Dave658, I know its been a while since your post, but if you still have any info/pics I would be grateful. I am about to take possession of a 2001 S Type and fancy fitting a reversing camera. I will be using a separate stand alone monitor.On an interesting side note - I fitted a reversing camera to my S-Type, not directly relevant to the original question as I removed the jaguar stereo and have a superb kenwood system instead that supports reversing cameraas right out of the box.
However, the point I wanted to bring up was that I bought a 25mm round camera with IR LEDs for mine, and I thought memebers may like to know that it fits right into the space where the boot release button usually sits without any need to drill. I don't think you need the exterior boot button, as you can open the boot from the dashboard or key fob, or even by key in an emergency, so I was willing to forgo this one extra button. It does have a nice "original" look to it now, and not needing to drill the boot is a definite advantage !
Beware of the depth however, the camera needs to be very shallow or it will foul on the aluminium skin itself
I will post pics if anyone is curious