Hi Damian,
just watched your latest video on the x100 cam chain tensioners which was very informative.
I have attached some photos of the original primary chain guides off my MY97 XK8, changed at 50k miles.
All the best.

 

Your guides appear to be in way worse shape than his, despite iirc 30k miles less traveled. l wonder what causes this? Short trips/commutes vs long trips?

 

Time is as much an enemy as mileage.
I change my engine oil once a year in most of my cars even though I only put several hundred miles on them annually.
I have seven cars that the wife and I drive so many don't go very far.
The FARM TRUCKS only go to town every few weeks (3 miles away).

Jaguar offered included services when I worked at the dealer. (every 10k miles or once a year)
We were authorized to do the service once a year if the mileage did not reach the 10k level.