Spoke to a jaguar electronics expert at Edinburgh he also says it won’t be the alternator or the battery more likely a bad earth somewhere like you all suggest or the bcm in the boot.
Hi Dave.
There is a sport button increasing the revs before changing gear.
I'm not sure what that would do but appreciate the input.
As I said, waiting 5 seconds from ignition to start up is working for now, keeping fingers crossed.
Cheers.
Graham.