Well,
fitting the socket took a few minutes
I do like the way Jaguar include little things like having the wiring already in situ.
Unfortunately, there is no power to the ignition controlled wire :(
Relay 10 in the boot fuse box and fuse 32 in the footwell fuse box seem to be the obvious candidates.
Unfortunately, it's hissing down here (would be of course, this being August Bank Holiday weekend), so diagnosis will have to wait until tomorrow.