Finally got my XK back to the dealer. Had a central junction box with some corrosion and they had to source one from England. I was getting repeated neutral safety switch warnings, engine temp warnings, cruise inoperable, and also engine cutting out above 4500 RPM's. Sure enough they were correct - all issues resolved.

thanks for the replies and just wanted to update the solution if anyone has any of the same issues.

almost 2k all in but I'm happy as a clam it's fixed! ( new box, new 2nd key, reprogram)