So, thanks to Alex Ward and a bit of research on the interweb, I now have Jaguar Voice enabled. The process is ridiculously easy as well, notwithstanding the fact that a mistake could brick the car.
Have to say that the Voice isn't as useful as that on my S-Type (No climate control functions)
Next retrofit is the six CD player. Already tried a straight swap and no go
Having had a good poke around in the CCF though I spied a function where the type of CD player could be defined. That, I think will be the next retrofit.
CCF editing is so much simpler than using the legacy SDD