Have you tried the battery charger trick yet in post #45? I get it, that's a lot of work, but as I see it, you still haven't ruled out low prestart voltage, so please don't poo-poo that idea.

And in the kindest manner possible, I wish you the best trying to troubleshoot with an engineer. From my experience, most engineers are absolutely brilliant at designing things, but not so at troubleshooting. I don't mean this as a knock on engineers, but often this just isn't their strong suit. It's hard to explain, just a different mindset, I guess.

Also, are you and Charlie9668 one and the same? Not sure if we're dealing with one or two people here.

Hi my car is a separate issue, I had enough of trying to figure out the issue so it is now at a jag specialist. I will post the outcome hopefully when they find it, but it is in a que of breakdowns.....

In answer to your 2 questions..........the battery approach , as everyone knows, would be the first thing to do. I've put a new battery in and made sure it is charged properly over longer than a week. Even had the guys at the workshop check the charging system and the state of the battery and a drop test too ( not that the drop test would make any difference) But the fact that it occurred outside my house and was cured of the message in about 10 seconds with not a battery charger in sight does tend to point away from the battery.
No I'm not Charlie9668.
As for engineers I do tend to agree with you mainly but the bloke helping me was there when these cars were prototypes at my place of work and is quite passionate about them. He is doing this in his spare time at work because he also wants to know WTF is going on out of curiosity more than anything. I guess you could say(and I hate cliche's) he is old school and very helpful as well as knows his way around the S Type.

Make sure the metal flap covering the key slot is working!!!
If this hangs and does not close properly this could be your problem.
Maybe some graphite lubricant while working the key in and out?

Can you see the cover at all with the key removed?
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The key cover looks like this:

https://cimg7.ibsrv.net/gimg/www.jag...435099f04a.jpg

Looks OK but maybe a bit open? I would still use some graphite and work it a bit.
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For a quick test, try the entry/exit feature for the seat and steering column. IIRC, you have to enable this feature with the Auto position of the switch on the side of the steering column. If you have the driver's seat all the way back, move it forward an inch or two. When you remove the key, the steering column should retract and the driver's seat will drive full aft to make it easier for the driver to get in and out of the car.

The issue with my car has now been resolved, it was the instrument cluster

Great news! Thanks for the update. To help the next guy, can you please elaborate how this was diagnosed?

The car went to Tom Lenthall Ltd jaguar specialist and when the car managed to start they got the codes. The main one they looked at was the instrument cluster fault so they replaced it with a used unit.

A few issues though, while the car has been with them it has come back with a cracked windscreen and a missing headlight washer cover. The cluster is also faulty as the fuel gauge does not work.

Tom Lenthall have said that the technician did not report the crack on the windscreen as apparently it was this way when they recived the car. I did get the car transported there and back, I know the guy who transported it and I would of expected him to tell me if the crack or missing cover was his fault. He has told me he only noticed the windscreen when he collected the car and didn't notice the cover missing. However I can not prove who it was so I am unsure when either happened.

I am waiting for a call back from Tom Lenthall on Tuesday when they expect the replacement cluster to come in, then I have to travel back to them to get the cluster replaced and coded once again.