I have a 2009 XF with a normally aspirated 4.2l V8 and approx 60k miles on the clock. So a lightly used vehicle.
Today, as I started the car, the motor generated a rattle that sounded like a badly adjusted tappet. The sound tracked the engine rpm. I shut the motor off but when I restarted it but the sound immediately returned.

I'd appreciate any thoughts on the likely causes before I head to the local jag workshops. Or links to other posts that will help

Thanks
Jim